Muncie SM420 synchro was the 4 speed that year , If it had a rod attached to the shiftier it would be pre 48 and no syncrhos
made from 1947 to 1967

https://www.novak-adapt.com/knowledge/transmissions/manual/sm420/


Dave Chapman
The Hollister Road Company
713-937-0387
[email protected]
www.hollisterroad.com
www.thoroco.com