The Master parts list , group 4.103 shows the 591615 as the transmission case casting number for a 1948-1954 Commercial 3 speed. This appears to be the correct transmission for your truck.

The 3686832 is the cover plate used on all 3 speed transmissions 48-54.

Hope this helps

Last edited by Dusty53; 01/13/2017 3:09 PM.
Ron - - Dusty53
1954 Chevy 3604
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