Those were good transmissions- - - -40 years ago or so. We ran them in 1/4 mile dirt trackers behind some high-revving small blocks and abused them terribly. A 1.88:1 2nd. gear against a 4.56 rear end gave an 8-something final drive ratio, and the box got hammered with full throttle several times a lap. The problem now is finding one that hasn't been blown up and rebuilt several times. About the only tougher transmission was the MOPAR "rock crusher" 4 speed that was used behind their high HP big block engines. Those boxes are even harder to find these days than the Muncie.
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!