I get all of mine from Moser. Just ordered another set today,but 30-spline. I rarely ever order 28-spline axles,unless I have to. The cost for the axles is exactly the same,and the cost of the Tru Trac is exactly the same for 28 or 30.
Gary. Great thing about Jim.(Monzaz) He has 30spline in stock. Never asked about 28. But ImI' sure. And most other parts. I called around Jegs Moser, ect. They said Buick axles are made to order. I've done business a few times with Jim. I just did the 30 spline upgrade. With his spider gear kit. Fair price and great service.
It should be a shelf item,like the c-clip axles,but they are not. They are considered a custom axle eventhough there were a gazillion of these rearends made.
It is just not as popular of a REAR AS 12 BOLT OR EVEN 10 BOLT CHEVY. That is why I just build them and shelf them...
I also wonder if they are not considered as much of a “wearable part”,like a c-clip axle,where the bearing actually rides on the shaft.