Drive shaft

Make sure it has the correct yokes on each end.I think the diameter has more to do with the yoke sizes, for OEM SBMs.
There are yokes for 7260 joints, and different yokes for 7290 joints. 7260s will not take 400ftlbs for long, if your car hooks.7290s will take it for a while, and then it's custom time for 1350s. On the street,with 275 or smaller street tires, you can run anything,behind an sbm.. It's not always the driveshaft that goes. My street car kept smashing the needles to bits. One time it it ripped the straps off the rear yoke, and the driveshaft plopped onto the pavement at about 30mph..
I have 1350 ends on my shaft now, a 1350 coming out the GearVendor, and a 7290 on the diff with an adapter-joint. No more troubles.I run 295 street tires. Cooper Cobras.They say those tires are crap, I dunno; they make real good skates.