Hi bigdog, I too have a 58' but its not a big window =( but I do have a piece of advice for you. even if the splines on the drive shaft fit the rear end and trans the length and drive angles may be askew. so what i would do is measure the distance between the tail comb (output shaft tip) of the transmission and and the yoke of the differential (after installation of course). take this measurement carefully and with info on your diff type and size along with trans info (type) and go to your local diff/driveline shop and they will either fabricate one for you or customize yours. if you are lucky enough the original driveline will fit but those chances are very slim. if at all possible let them make the measurement each shop has dissimilar procedures. However on the other hand if the yoke splines on the drive shaft fit splines on the trans then all you need to worry about is length. be careful if measuring the driveline itself because some shops measure from weld to weld and others from the center of the u-joint bearing caps at each end. hope this helps.

Shovel all the coal in, gotta keep it rollin! .
1958 Chevrolet Apache "32"