Have you checked ebay?

https://www.ebay.com/itm/324892710154

There are other parts needed to make this transmission work.

It case you didn't know, the early transmissions did not have synchronized first and reverse.
You have to slow down or stop to shift else you get gear grind.

"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."