The only difference in a SM 318 transmission case and a 319 is one hole drilled for the lockout pin that disengages the OD when reverse is selected. With a very rigid drill press with no spindle run-out or a Bridgeport mill and a chucking reamer, it's possible to make a 318 case work with the B-W OD unit.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!