Chevy/GMC 89-91 Grill Swap

May. 01, 2000 By Neil Pickett

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Want to give your old Chevy/GMC a face lift? One of the latest trends is to update the older ‘73-’80 front clip to the clean lines of the ‘89-’91 style front clip. This page will, in a lengthy process, explain this type of swap. If you are interested in only upgrading your ‘81-’88 grille to the ‘89-’91 grille, see the Parts List then skip to the ‘89-’91 Grille Installation section.

Before

After

Like most of you, I have a Blazer “Project” that will never end. I bought my 1978 K5 complete with parts truck at a good price. The problem is, I was wanting the ‘89-’91 years. Not long after buying my ’78, I wanted the newer ‘81-’91 style front clip so I decided to upgrade. I started the upgrade by searching the newspaper and salvage yards for any ‘81-’91 Blazer or Suburban I could find. My search ended after looking in the local newspaper and reading about an ’82 Suburban front clip. I made the purchase and arranged shipment. I bought the complete front clip including: Radiator Support; Fenders with side marker lights and inner fenders; Hood, hinges, and springs; Headlights, Buckets, and trim rings; Bumper with turn signals; Grille, Headlight doors, and Chrome trim surrounding the grille. There were some parts not included which I will detail later. I was in a hurry to get rid of about 20% of the rust from my vehicle so I started the project right away. I removed the existing front clip all in one piece with the help of some friends. I did not; however discard my radiator or headlight wiring harness. Disconnect your factory hood latch cable if equipped, this will be reused for the new latch. At this point, you may want to replace the radiator support mounting bushings and bolts. I completed my ’82 front clip upgrade previously. After seeing the Off-road.com Project Blazer “Potent Rodent”, I decided to upgrade mine again. Shawn Spickler, owner of the Potent Rodent completed a similar swap on his ’87 Blazer. In the parts list, I have noted some GM part numbers for your use. Most body shop supplies can use these numbers to find the correct part the first time (it took me several trips to the store). Lets talk parts.

Parts List:
‘89-’91 Radiator support GM part #15641713 *
‘89-’91 Grille (center portion) GM part #15628796 *
‘89-’91 Right headlight/turn signal bezel GM part #15628670 *
‘89-’91 Left headlight/turn signal bezel GM part #15628669 *
4 - ‘89-’91 Headlights, headlight buckets and trim rings GM part #16503172 (RH low beam), 16503171 (RH high beam), 16503162 (LH low beam), 16503161 (LH high beam)
‘89-’91 Right Turn signal lens GM part #5975228 *
‘89-’91 Left Turn signal lens GM part #5975227 *
4 - ‘89-’91 Headlight “pigtails” *
8 - ‘89-’91 Headlight adjusters *
4 - ‘89-’91 Headlight springs *
‘81-’91 Right fender GM part #15634642
‘81-’91 Left fender GM part #15614467
‘81-’91 Right inner fender GM part #15594890
‘81-’91 Left inner fender GM part #15594889
‘81-’91 Hood GM part #15629509
‘81-’91 Cowl panel, plastic leaf cover, washer spray tubes and hoses
‘81-’91 Wiper arms, linkage, and posts
‘81-’91 Battery tray
‘81-’91 Washer fluid reservoir and hoses
‘81-’91 Hood weather strip, hood bumpers (on fenders), hood stop adjusters (radiator support)
‘81-91 Hood latch, hinges, hinge springs, hood hinge foam seal (one per side) *only used in the ‘89-’91 grille swap for ‘81-’88 Chevy/GMC Trucks.

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Radiator Support, Fenders, Hood and Hinges
When I upgraded to the ’82 front clip, I followed these steps. Install the radiator support, radiator and shroud. I used my existing ’78 radiator and shroud. The next few steps are a bit complicated and require installation and removal of the fenders and hood. View the images, then mark and cut two rectangle holes in the firewall for hinge recess. Bolt the fenders and inner fenders onto the truck only using a few bolts to line up the parts. Be sure to tighten these bolts after aligning the panels because you will be making some measurements for the hood mounting hinges. After installing the fenders, install the hood hinge spring to the fender and let it hang down out of the way for now. Next install the hood hinges on the hood. Make sure the hood latch is installed in the radiator support. Have a friend help you install the hood and hinges in the correct location. After installing the hood, line it up with the front and top of the fenders. Next mark the holes where the hinge mounts on top of the firewall (2 holes on each side). After making sure the hood is perfectly lined up and you are sure of the holes you have marked, remove the hood. There are several options you may have here. I did not have enough metal on the outside of the firewall to drill holes and mount the hinges. My Blazer required me to either weld an extra piece of metal to the firewall for the new hinges, or simply weld the hinge mounting brackets to the firewall and be done with it. I opted for the latter. If you plan to weld the hinge directly to the firewall, be sure to elongate the hood mounting holes for adjustment. The bad thing about this option is, you must get the hood perfectly lined up so you have plenty of adjustment when you elongate the holes. When I did final welding I kept the fenders in place and spot welded the hinges in place. I then checked how the hood opened and shut and made sure I could adjust it properly before welding firmly. After welding the hinges or bolting if you have the holes drilled, install the rest of the bolts for the fenders. If you opted to weld your hinges on, you will have to attach your Hinge foam with weather strip adhesive. I do recommend using the foam, at least on the passenger side hinge, as you will be drawing cold air into your fan in the winter months. This will help keep most of the cold air out. Install battery tray in the factory location, side marker lights and horns

Hinge Detail

Hinge recess hole
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Windshield Wipers and Cowl Panel
The next item to install is the Windshield wiper linkage and posts. The new posts are longer than the ‘73-’80 style. The posts fit in the same hole as the existing posts, but you will have to drill out one new hole per side. The posts have 3 bolts per side but they have one hole off a little. Next install the cowl panel. The new cowl panel is anchored by 1 screw onto each hinge and plastic anchors that mount in holes in the fire wall. The ‘73-’80 firewall will not have the holes, so you can either mark and drill holes or not use any of the plastic anchors. The two screws keep mine secure without flopping. Install wiper reservoir on the fender in the factory location. Hook up the hoses to the washer pump and to the washer spray tubes in the cowl panel. Install the washer fluid reservoir and connect hoses to the pump. ‘89-’91 Grille Installation

After installing the radiator support in the factory location, bolt it to the frame with 2 bolts, then attach to the fenders and inner fenders. Place headlight into each cup and install trim ring. Install adjusters into radiator support (8 total), then install each headlight assembly and spring. Adjust the headlights until they appear flat at this time. You can adjust the headlights after completing the installation. Install turn signals on each side with four attaching bolts.

When installing the grille, you will notice some attaching points are missing on your front valance. Fabricate some “L” shaped brackets and rivet to your valance. Drill 3/8” holes in the brackets after aligning the grille and marking the center point of each hole. Install factory style nutsert into the hole. Install grille. You will need to drill and elongate a hole for the lower mounting point for the bezels. After making the hole, install factory nutsert in the elongated hole. Install right and left headlight bezel. Your grille at least “looks” like a ’91, now lets talk about wiring to make the change over more functional.
Wiring Installation
The new headlight system is a single filament style where most earlier versions are double. The upgrade will require some minor wiring to enable the lights to work properly. The turnsignals have a small plug for the parking lights and a big plug for turnsignals. The side marker light uses the same small plug as any ‘73-’91 Blazer/Suburban/Jimmy. I researched this topic and found several sources.

The “pigtails” I referred to in the parts list are actually short pieces of the factory wiring harness wires and the plugs that attach to the headlights. Call local junkyards looking for the specific years (‘89-’91) of Blazer/Suburban/Jimmy. If this doesn’t pan out, call the local Auto Parts stores and ask for the headlight wiring plugs. Still no luck, as a last resort call GM Dealer. The Dealer pricing is extremely high compared to what you get. I lucked out and found a wrecked ’90 Suburban with the dual headlights. I purchased the complete headlight wiring harness for a mere $75. That price seems like alot when you see the small pile of wires, but ease of installation will far outweigh the price. My splice was made about 12 inches from where the wires leave the firewall. I think I could have just used the factory ’90 Suburban plug and installed the Brake fluid warning light wire into the new harness. The splice was easy because the wires were all the same color as my ’78 wiring harness. The only difference in the splice connection of the new to the old is the new harness has two extra wires. The two wires are Dark Blue and Light Blue. After viewing the Wiring Diagram, I noticed the two extra wires are to be connected to each other. After making a quick splice, I re-connected the Battery and tested the lights. They work great. Test all the lights by toggling your turnsignals; high and low beams, park lights, etc. When faced with doing the wiring challenge, you have some options. These models use the same style of headlight and turnsignal plugs:

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‘89-’91 Chevy Blazer/Suburban and GMC Jimmy w/dual headlights - see Option A
‘89-’91 Chevy/GMC Truck w/dual headlights (headlight plugs only) - see Option B
‘92-’96 Chevy/GMC Van w/dual headlights - see Option C

Option A - Find a wrecked ‘89-’91 Blazer/Suburban/Jimmy at a salvage yard and purchase the headlight wiring harness. Be sure to keep it intact and try to get the factory plug from the firewall. See the Wiring Diagram to connect the new harness to your old style like my ’78. Option B - This is where good old ingenuity comes in to play. Find a wrecked ’89-’91 Chevy/GMC Truck w/dual headlights at a salvage yard and purchase the headlight “pigtails”. You can wire the new “pigtails” into your existing harness, keep your existing side marker light plugs (from ‘73-‘91are the same); keep your turnsignal plugs (from ‘73-‘91are “close to” the same) and plug them into the large hole on the turnsignal assembly; lastly obtain some side marker “pigtails” from any ‘73-’91 Blazer/Suburban/Jimmy or Chevy/GMC Truck and splice into the existing side marker lights then plug into the small hole on the turnsignal assembly. Option C - Find a wrecked ‘92-‘96 Chevy/GMC Van w/dual headlights at a salvage yard and purchase the headlight wiring harness. This headlight wiring harness is the same as the Blazer/Suburban/Jimmy. You can cut the plug off the end (at firewall) and splice into your existing wiring. When purchasing your wiring, make sure you have enough length to attach to the new locations. For headlight wiring, review the Wiring Diagram provided. While at the salvage yard getting your wiring harness, search for headlight buckets, adjusters, bolts, nutserts, and hardware. This will simplify the installation and could save you time and money.

Wiring Diagram