Looking for a new driveshaft

If you are going to change things, then get away from the detroit stuff altogether...

The 7260 is a little smaller then spicer 1310, and the 7290 is a little bigger then 1330 series caps.

You can go to 1310 or if you want 1330 or 1350, you'll have to change the end yoke on the diff and the slip yoke to the series you want to go with...

Then have the shaft made with 1 of the 3 choices above..

Keep in mind that the spicer spl line of joints in 1310 will easily handle 800hp.

I would also steer you to an AL shaft, in the performance world weight lost in the driveline is big for performance.... so going from a 24 or something pound shaft to 11 of 14 pounds is a large difference... very similar to losing 150 to 250 pounds of carrying weight...