trunnion to universal swap

Can I switch to a universal type driveshaft, from a ball/trunnion type without changing at the rear? I assume that both ends of the driveshaft need to be switched? I am planning a 64 Polara restification, and would like to update several areas.

Nope. You need to change the front of the shaft, and either the trans, or the output shaft. If you're talking about an automatic, you may have to go to the one year only 65 output shaft, cause those early 727s has a front and rear pump. After 65 only a front.

Yes you can. The rear end still has the standard Ujoint. Get A drive shaft from a 1/2 ton Dodge Power Wagon with a splined shaft and the C/V joint.( unbolts from the transfer case)Take them and your original to A drive shaft shop and have them make one up.