C1 Upper Fender Molding Nuts

[Rick C.]

These are the speed nuts that were on my '62 upper fender moldings. Can anyone confirm whether or not they are the correct size? They seem a little small. OD is 7/16" and uses a 5/16" wrench. Thanks!!
Rick speed nut for top fender molding 2.jpg

[Gary B.]

Rick,

Someone might be able to tell you more about those speed nuts if you provide the GM part number from the AIM.

Gary

[Rick C.]

Thanks, Gary. Part number is 3789888 which was later changed to 3752642. I have the earlier part.
Rick

[Gary B.]

Rick,

Based on my not finding any results from Google and eBay searches for 3789888, I suspect it was never available as a service replacement part. Whereas 3752642 was available as a service replacement part, and it has been reproduced. But there is no guarantee that the 3752642 part has the same OD, wrench size or finish as the 3789888 item. For my ‘66, many of the original Pal or speed nuts had a dark finish, whereas the reproduction speed nuts I’ve seen have a lighter finish, like the one in your photo. Maybe zinc plated?

Gary

[David B.]

Look at the speed nuts used on your front fender name plate & ornament. 3752642 is the same nut used on the upper molding assembly. can be found in Grp. 8.147 & 12.182 type M - 1/8 hole