Can anyone tell me how long this little critter is?
I need to know how much of it should be sticking out of the case to make
contact with the tranny mainshaft thrust washer, and where i might find one if needed to be replaced.
Its pt# 600 in my parts book, if that helps.................

 

It only needs to stick out of the case by the thickness of the mainshaft thrust washer tag. Just enough to stop the washer rotating.

Roll pins are available from engineering and bearing supply shops. If too long, you can cut them down with an angle grinder.

Or you could just order the HD part.

 

The pin should extend 3/16" +-1/16" into the case the pin size is 1/8" x 9/16" spring steel roll pin. The hole depth is 3/8".