Mod75

Installed the fan shroud extension i found up in the rafters, has been off for 30 plus years. The bolt holes at 10,12,and 2 o'clock look like they are 1/4 20 threads into plastic.
The two at 4 and 8 are steel inserts and look like they might be 5/32.

Any body have some info on what size bolts should be used?
Its for a 75 coupe, my aim book doesn't make it very clear what to use.

noonie

Going from memory here, but I think the size was 10-24 and they were all "t" nuts. It was common for them to disappear.
For bolts I used all stainless socket button head, but the originals were hex head with larger washers.

7T1vette

They need 10-24 screws. The T-nuts for the 'sides' are built into the radiator shroud. The T-nut for the bottom is built into the shroud extension. If they are not present, you can replace them with T-nuts from a hardware store.

Mod75

They are indeed 10/24 threads, just came back from Menard's.
All of my T-nuts where gone so i got replacements for them and some stainless button heads to finish the project.

My guess at 5/32 way off, was because there was a 5/23 T-nut stuck inside of the extension housing

Thanks to all for the info and pic.