clutch fork ball stud length

[Jeff M.]

GM lists 2 of them as follows p/n 3790556 is 1.68" long and p/n 3729000 is 1.380 long. What is the correct one for the 621 bell housing for my 71 big block. I believe it is the long one

[Joe L.]

Re: clutch fork ball stud length

Jeff-----

Your car originally used clutch fork ball stud GM #3887159. This stud had an overall length of 1-3/8". It was used for 1966 to 1975 Corvette applications. It was discontinued years ago and replaced, for SERVICE, by stud GM #3729000 which has an overall length of 1-1/2". The latter stud was originally used for all 1955-65 and 1975-81 Corvette applications. It will SERVICE the 66-75 applications just fine.

Stud GM #3790556 was never originally used for any Corvette application regardless of what some parts references might say.