rear end u-joint

[Jeff w Ashworth]

I put a 85 k20 suburban rear end in my 84 half ton and saw the u-joint was different can someone tell me what u-joint I need to fit it now, the half ton u-joint caps are smaller around the k20 one.

 

[PrairieDrifter]

The half ton should be a 3r, then the 20 should be a 1310 or 1350