7.25 to 8.75 swap questions

The 7260 series is considered the "small" Mopar u-joint and the 7290 is considered the "large" Mopar u-joint. The "small" 7260 series fits a yoke that has an inside span of 2.125" . The "large" 7290 series fits a yoke with an inside span of 2.625". If you end up with a rear axle with the large yoke you can use one of the following u-joints to adapt your smaller drive shaft to the large yoke.
Mopar P5007418
Spicer 5-527x
TRW 20226
Precision 347
Napa 240-0369