it'd either be the smaller 7260 which iirc is 2&1/8 from inside to inside on a pair of ears on the shaft or a 7290 which is 2&5/8" (I hope my dimentions are correct, measure yours) & likely that might account for the discrepency in the listings (showing 2 numbers). After installing on the bench confirm the yoke in front moves smoothly thru both planes of travel & the rear ujoint moves smoothly thru its single plane of travel (whack the 2 connector "ears" on each end of the shaft with a medium BFH as needed) & make sure the zerk is in compression. confirm no needle bearings fell down during the install. EDIT an eBay listing says it is a 7260 & 2&1/8" is correct & a 1.078" bearing cap O.D. MORE EDIT consider haveing the shaft balanced (or at least checked by a competent shop) that balances for HIGH RPM (some balance too low). You might talk to Doc