Two birds with one stone: Get the Saginaw and dump the tube and rear end. Get a 3.08 or 3.42 for hiway or the perfect all around ratio: 3.73. No adaptor needed. 4 speed Saginaw has three shift levers and ID from the web. There are several ratios of them , identified by the grooves on the input shaft. Price varies. $150-$400 , get the shifter with it if you can. There is one on San Diego/OC craigslist now for $200. And one in L.A. with clutch, bell housing, fly wheel, Hurst shifter and the trans is rebuilt for $600.(3 groove)...Hesperia with Bell housing $180 (3 groove). They have shaft size and spline count differences, I think, so be real sure it fits your setup before you buy. Also check clearance to truck bench seat. Buckets? No problem.
Saginaw 4-speed 1st 2nd 3rd 4th (according to the web)
No grooves 2.84 2.01 1.35 1.00
1 groove 2.54 1.80 1.44 1.00
2 grooves 3.11 2.20 1.47 1.00
3 grooves 3.50 2.47 1.65 1.00
