converting to bbp 11x2 drums
so is that why there is a difference between the moser axles?
Yes. SBP A body axles use a different offset than everything else out there, so
only SBP backing plates and brakes work with SBP A body axles.
So, there are two ways to change over to BBP. One is to re-use your SBP, A-body brakes with re-drilled drums. If you do this, your axles need to have the stock SBP A-body offset regardless of the new bolt pattern.
The other way is to change over to the BBP brakes used on everything else (10x2.5, 11x2, 11x2.5, 11x3). Stock BBP axles all had the same offset, so those brakes are all interchangeable with the same set of axles.
I do all of my business with Dr. Diff, Cass is awesome. :thumbup: But, regardless of where you get your axles, the important part is to tell them what brakes you're planning on running, because that will dictate which offset your axles have.
I think its easier just to use the BBP brakes, no redrilling needed, and no issues finding drums or brake parts, the 10x2.5" variety came on pretty much EVERYTHING up until around 1991. Drums for the SBP brakes (10x1.75") are getting harder to come by, and of course every time you need new drums you'll have to have them drilled for the larger pattern.
The 11x2" brakes you already have use the BBP axle offset, so no worries there. But 11x2" drums and hardware are a little harder to come by than 10x2.5 or even 11x2.5" stuff. Still easier to find than the SBP parts though, and if you already have them you might as well use them. Just let your axle provider know that you're going to use C body or BBP brakes and that you're NOT going to use redrilled A body brakes.