Okay, I have read a lot of the previous posted info, and the answer seems apparent because they only sell one kit. But.....

I am swapping 26 spline for 28 spline axles as part of a zexel upgrade. Will I need a different size axel bearing? (Wheel Bearing) They are different diameter shafts right?

Do they just include both in the bearing kits? I plan to order Ratech kit #3001K
7.5" & 7.625" GM Axle

They use the same bearing; that part of the axle is the same diameter.

Some of the axle kits out there, such as the Superior ones, come with new axle bearings and seals; so check what you're buying, maybe you don't need to buy the more expensive kit.

Superior Axle and Gear Evolution Series Rear Axle Kits: SAG-EV10-4 - summitracing.com

Thanks for the definate answer! This is what I assumed because it flares out there.