I have a 1980 C3 I bought about 12 years ago. It was my daily driver for over 5 years, but things change (kid), so it has been sitting in my garage for about 6 years, and I am getting the bug to get it running and make my daily driver again. From what I can see without tearing it apart, it looks to still be in great shape as far as corrosion goes. When I put it away, it was bone stock, and I had to do the weekly fluids top off...I really want to get a drop on frame, but that would get wildly expensive. i was looking at the ridetech kits, but they stop at 79, and I didn't see one for the 80-82. Does anyone make a nice coil over (front and rear) for a 1980? I would probably pull the body off, stiffen up the frame and get the rolling chassis tip top. New brakes (I always had to screw with the emergency brake to get it to pass inspection every year). I am thinking I will get a lq4 drop out (still lighter than the 350 that is coming out of it) and beef it up a little, then get a magnum t56 to mate it to. Nothing too crazy, but 450 HP rowing through gears with the t-tops off would be amazing again. Any suggestions on suspension kits?

 

I am very interested in seeing how you make out with the LQ4 swap. I am wondering how much room there will be for a turbo and intercooler setup

 

I pieced together a rear end on my 80 and am quite happy with the results. Just replacing the rear strut rods with heim-joints will make a tremendous difference. To do it again, I'd have to go with a Van Steel rear spring (I bought possibly the last NOS VB&P spring from a Forum member). Otherwise, you'll have to change out the rear differential for a 79-style with separate crossmember. Rear stance is easy to adjust, though, so you may not need coil-overs in the rear.

The front suspension is a possible winter project. You don't need to buy a kit, just all new bushings, and a coil-over setup. SpeedDirect will sell you custom coils for the QA-1 double-adjustable coil-overs, and may be able to sell you just what you want the first time. I have a GTR1999 rebuilt steering box ready to swap in, and I've already converted over to manual steering.

A local shop had a wrecked, LQ9 Silverado 2500HD parked outside for a while. I asked about it a few times, but it seemed the owner was intending to swap engines with a non-wrecked 2500HD the shop also owned. It's not there anymore in any case. I should have tried harder, not that I need another project.

EDIT: Here's the BOM for the rear-end (the swaybar is waiting for the front rebuild before getting installed)

385 lb VB&P composite leaf spring (360, shortened an inch at the factory)
The spring bolts the spring came with (lowered the car an inch anyway, at the "longest" setting, perfect)
Bilstein Sport shocks
Heim-jointed strut rods from Mid-America
OEM-style sway bar mounts
OEM 9/16" sway bar, used, from a Forum member
Poly sway bar bushings
Stainless braided brake lines
Rebuilt trailing arms including new brake rotors
Rebuilt (by me) rear calipers, with "high-heat" CSSB o-ring kits