Brake Drum Width?

Ok, let me get this straight.

You have BBP Yukon axles.

You're trying to use SBP drum brakes. 1 3/4" shoes only came with SBP brakes. Did you have the SBP drums re-drilled for BBP?

Either way, you can't use SBP brakes on a BBP axle, or vice versa. The axle offset is different, SBP brakes only work with SBP axles. And not because of the bolt pattern, the axle stand off (offset) is different, so drilling the drums doesn't solve the problem.

If you have BBP axles, then you need to find a set of BBP brakes. Those would be 10x2.5, 11x2.5, 11x2, or even 11x3. All of the BBP brakes use the same offset (backing plates are different on the 2" and 3" brakes). 10x2.5" brakes are pretty easy to find at the junkyard.