The syncronized trans was an option, could probably find one in any GM car/truck. 1966 and later had the syncro trans, you just have to look. Like fat fenders said the numbers are stamped on the tailshaft housing, there is also a govenor( small round thing) on the passenger side rear tailhousing, and a rather large solenoid(large round thing about 4 inches long) on the right side of tail housing.The shifter arms of the two transmissions are completely different so you will have to get creative to use the original column shifter. Now if you find a non syncronized overdrive trans it will be a bolt in. good luck.
