The Stovebolt Site Forums The Shop Area Engine Shop numbers game

The numbers on my tranny are like this: on the drivers side, E246 on the top line, then 8 on the second line, GM on the third line, and 3837334 on the fourth line. In raised characters on the back end of the trans are these: 681701 first line, GM on the second line, and 10 on the third line. I can guess the GM part......but does anyone have a translation for the others? It is a four speed with reverse to the down and to the left, PTO take off cover on the drivers side, and no major ribbing I can see on either side.

3837334 is the casting number for the case of an SM420 from '63-'67 series 10 thru 30 trucks. I think these later SM420's were a "second design". Your case casting date E246 would translate as May 24, 1966.

681701 is the casting/part number for the rear bearing retainer, though I don't find that number in my parts books. It looks like this tranny may have that number on the rear retainer. I did find a 591701 for the retainer on the '48-'64 models, but that number should be stamped, not raised.