Hello, My O.E.M. rear brackets were toast. Unusable. I did use the aftermarket brackets, and all went well.  As for the supports internally, they too did not remove easily. Some were unrepairable, and corroded. I used a flex fit rear bumper. Still did not fit well. Had to reform the lower quarter panels to blend it in. 1/4 to 3/8 on both sides. Looks good and painted entire car. 

Wow turned out nice! I got all the bolts in mine and tightened over the weekend for the rear. The front i put what i hope is the last of the fiberglass. Will sand it and see where im at. The rear as about 1/4 inch narrower all around so shouldnt be bad fiberglassing. I had ome spot on the body that cracked about 3 inches when i tightened the bolts. I will just drill a hole at either end to stop it further splitting and glass it. 

Vette looks awesome! Im contemplating going like a black 3.0 and some flake over it afterwards... im a ways away from the finished paint yet. Gettimg it running a few weeks ago gabe me that motivatiom to get back on it

Just a quick note, when replacing the rear bumper on my 75 with a Truflex, once the bumper was removed, we started looking around the tank and shield area for any additional work required, to our surprise we located the factory build sheet tucked in toward the fuel tank shield. Might be worth having a good look around the area while the bumper assembly is removed and the access is improved.

HI,

I installed front and rear Fiberglass covers on my 80.  I also did not like the idea of just using a hole and the fiberglass to hold the light assembly in.  I cut the fiberglass to accept the original metal rings for mounting the tail lights.  I feel it is stronger and I don't think there is any concern for vibration or stress on the cover.  I did have to do a lot of body work to get an exact fit on both the front and rear.  The original urethane could stretch a bit, and I found lots of high build primer that was used to even out the fit.  One caution when sanding these covers, they seem to have pin holes and some of those turn into voids in the fiberglass.  I had to repair several voids, especially in the rear cover fitment. They are definitely not plug and play.  I didn't care for how much mounting lip there was on the fwd cover.  That's the flange type of area where the attachments are for mounting to the front fenders.  I added more fiberglass so the attachment brackets had plenty of surface area to even out the stress.  I might be a little obsessive, but I work on airplanes, so I tend to push the cautious side of repairs.    I do like the look of these now that they are fitted.   Here is some of the work needed on the rear cover.

Yours looks like a good fitment. I have about 1/8" across the top and about 1/4" along the sides that the bumper needs filled.  

Nothing compares to the body lines on these C3's. I also went with that year bumper on the rear because i like the fin. I put a rebuild kit on the quadrajet a couple weeks ago, and just being able to drive it down the road got me motivated again, as that rear bumper sat in the corner of my garage for the past year. And by no means am i a body repair expert so im learning as i go. I bet i took bondo 3/4" thick off this thing from the previous owner who filled the seams and the bondo pulled loose from the original bumpers. Im hoping i dont have that issue with the front, which is why i tried to get basically a fiberglass shell over the entire top and sides. I contemplated getting one for front, but realized the amount of work just for the rear, might a been taking on more than i can handle. Post more pictures as you make progress amd i will do the same