I’m not sure these GMC ‘s had an acorn nut to begin with. Most of the GMC’s that have come through the door have a stepped or tapered hex nut. The aftermarket grommets fit like you are experiencing. I have used a thin SS washer on top to help seat. The grommet just helps seal the gap between the threaded rod and the cover. Just torque the bolt or nut enough to seal and catch as many threads as you can... or turn out and raise the threaded rod enough to secure that top hex nut or acorn.
But yes, start with a flat cover... read the manual. It may say use a silicone type sealant on the cover and gasket. Or the cover may not use a sealant. Can’t remember what the manual says. I use Ultra Black and lightly place the gasket into the cover after letting it set up for 10 minutes. Then I lightly press the cover down with nuts, wait 10 minutes, then do it again. Maybe overkill but it seems to allow the gasket and sealant to mold to any irregularities.
Repainting is just taking time to do it over. Call it a casualty of the war.
BTW - nice paint job. What paint did you use? I used Jim Carter green for the early GMC’s but it laid down glossy. I like the flat paint.
Last edited by tom moore; 11/19/2020 2:50 AM.
