Originally Posted by big gear head
Powerglide wasn't produced until '62. Earlier aluminum 2 speed was a Turboglide from '58 to '61.
Oops, I forgot to say the aluminum Powerglide. As far as I know the cast iron Powerglide was replaced by the Turboglide in '58, but I've been wrong many, many times before. But what difference doe it make anyway.
To replace the transmission that you have now will at least require changing the yoke on the drive shaft. The early transmissions had a coarse spline shaft. The TH350 and other later transmissions had a 27 spline shaft.