There should be a common bolt,used most of the time,but not 100% of the time. The assemblers used what was supplied,and there were times that the supply changed. You could literally have one style of bolt on one side of the car,and a different style on the other. Then there were the different plants and what fasteners they were supplied with. I know I have those bolts with the dish and the crosshair. With and without the washer. It’s just a matter of finding the correct container. Having a frame fall over and crush your foot does not exactly motivate one to continue the search.
I wonder why Brett hasn’t implicated me in this? I put the bug in his ear. The lower alternator arm bolt had a weird length. 1 5/16” I believe.
Dave, I always thought you were a "behind the scenes" instigator. I on the other hand usually come out big and bold. Duane
Brad that’s a shoulder flange screw. Pretty much established that’s not correct. That’s the type used to attach the AC compressor. Those were 3/8” though.
I removed the alternator adjustment bolt and washer also lower bolt from the arm. I believe these to be original to my 4 speed 69.
Those are pictures of the 3 bolt I found. Not sure if any are right, but they all work. One of them appears to have GM on it, or 6M???
In a drawer I have marked alternator I have an indented head(now gone)as well as two TR and an SB, I would say all are correct and most likely agrees with what is showing up now. Brett was right with the indented head but so were the guys with the plain type TR, SB heads. Only guys losing out here are the washer and flange head guys. Sorry guys. For anyone interested that lower alternator arm bolt is available from AMK which is pretty much a small miracle. It has a non threaded area where it passes through the arm and water pump my guess so threads would not rust. It is an oddball length. I used it on my GSX. It has a cockeyed TR for some reason I can’t figure out but who will notice?
Dave, is it just the shadows or is the upper bolt which is bottom in picture a fatter than 5/16” bolt? It just looks it? Also what is the length of upper alternator bolt you have. That has never really been answered. I have a few one inch under head length but also one 1 1/4”