R10 Info:

Borrowed from the Internet:
The only overdrives which ever came on GM cars were R10 units which were bolted to the (4 bolt side cover) Muncie transmission SM319 or the later Saginaw trans (7 bolt side cover) SM326. You will find "R10" cast into the OD housing followed by a letter which indicates the original application. Following are the letters I have found on GM units so far. This is not to say there aren't others.
H - 55-57 Muncie w/o rear mount - 16 spline output
K - 58-63 Muncie with rear mount - 16 splines
P - 64-65 Muncie - 27 spline output
Q - 66-69 Saginaw only - 27 splines

Limited time preview of operator's manual on this website:
https://www.scribd.com/document/433324460/bwoperators-pdf

Last edited by buoymaker; 01/05/2021 4:32 AM.
"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."