Hard to find combination U-joint mates a standard, small 7260 Mopar pinion yoke to a large, heavy duty Spicer type 1350 driveshaft.
I don't recommend using the 7260/1350 conversion joint to mate a 7260 driveshaft to a 1350 pinion yoke or 1350 transmission yoke. Due to the large diameter of the U-joint body, you must grind the edge of 2 bearing journals at a 45 degree angle to install the cross into a 7260 weld yoke or 7260 transmission yoke.
PLEASE CHECK THESE DIMENSIONS TO MAKE SURE THIS IS THE PART YOU NEED!
1350 U-joint dimensions: 1.188" cap diameter x 3.628" overall width
7260 U-joint dimensions: 1.0625" cap diameter with grooves x 3.250" overall width