‘79 K20 Camper Special U-joints

[zac]

Replacing my rear driveshaft with a better one with no slip yoke wear, swapping the u joints first. I always have trouble looking up parts for this truck because of the weird combination of parts. 10 bolt front, NP203/TH400 with a 14FF rear axle. The Rockauto Autozone, whatever references are almost always wrong. I pulled the old ones off, likely the originals. The transfer case end says Spicer P621. I believe the new Spicer # is 5-760X. Its not greasable, I wouldn’t mind having one that is. The axle end u joint is larger, caps 1-3/8” approximately. One side says “Spicer Can” with numbers F3-5-69 and a big X in the middle. The other side says A525. None of these numbers are helpful when trying to look it up. I’m hoping the 14FF used a standard u joint and somebody here knows the part number.