Where did you get that info John? I measured again to be sure and I measure the small 7260 joint at 1.078 and the 7290 at 1.126 The following paragraph is copied from a tech arcticle on the Moparts board. Heres the url if you want to read the complete article. It's got alot of info on the 8-3/4.
quote [The 8-3/4" axle was offered with two size cross & roller style universal joint. These are referred to as the '7260' (2-1/8" yoke ID) and the '7290' (2-5/8" yoke ID). Most Imperials and some C-bodies used a different univer-sal joint. The '1330' type joint was used on Imperials and others with a constant velocity joint. The '1330' uses outside snap rings instead of the inside snap rings used by the '7260' and '7290'. The cap diameter for the '7260' is 1.078". The cap diameter for the '7290' is 1.126". The '1330' style joint cap diameter is 1.063".] end quote