The cast iron Powerglides from 1950-54 were enclosed driveshafts. The '53-54 are the better of the lot, they started out in low and upshifted to high themselves. The 1950-52 transmissions had to be manually shifted from low to high, or you just started out in high and let the torque converter slip like crazy and ooooooooooooozzzed away from a stop....LOL
John
