^ given towing and nose rise, tha's a good idea to lower the front a bit. I' in the same boat and i'm considering changing springs to lower the nose and keep axles hapy under DD and towing...
So, I just called and spoke with the product manager from Heri's Phoenix location, yesterday. He shows plenty of 22200s in the States but that there currently are no 22276s and none currently being shipped across the Pacific so they must be backlogged in production.
They've been getting some heavy press (like here) and were only introduced at SEMA in November last year. He said they've really only been on shelves for about 6 months or so and are already COMPLETELY OUT OF ALL 22276s in the USA.
He did mention there are slight differences b/t the 22276 and the 22200, and here's my summary: Mainly there are slight differences in length between center hold for the roll pin and end of the dust cup/collar around the trans stud, but as E.J.'s pointed out, with the tone ring (and ABS fitment I think) gone their mounting is virtually identical to the 76.
Here's his actual quote, "According to my engineer, other than the ABS on the 22200, there are slight differences between the 22200 and the 22276. Specifically the collar diameter on the IBJ and distance between the end of the collar and the center of the roll pin.
This is the IBJ on the 22276. If you have an old axle laying around you might compare the 2. The overall length is the same."
While he was not at liberty to reveal too much technical detail or imagery, he did share the following images.
22200
22200: compressed length 26 9/16”; IBJ splines 25; OBJ splines 27; IBJ female
22276
22276: compressed length 26 14/16”; IBJ splines 25; OBJ splines 27; IBJ female