Originally Posted by klhansen
My take on why there's a stud instead of a bolt on the top mount is that it's easier to stick the starter over the stud than to hold the starter in position and start a bolt. Anything that makes assembly quicker at the factory is usually done. The starter lines up in the hole for the nose, but can be out of rotation to find the hole for the bolt (instead of stud situation.)
The stud is coarse thread on the end that screws into the bell housing, so strength at that point is basically the same as using a bolt. Why a fine thread is used on the stud/nut is still a question in my mind.
I believe that fine thread nuts do a better job of staying in place than course threads. Maybe has to do with more friction imparted by the additional number of threads.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission