It looks like the bolts holding the drum to the hub are the issue. I put the old drum back on and had the same issue. The bolts don't affect the stock wheels, but don't let the new wheels fit flush.




Old drum with bolts removed now fits.





New drum with bolts removed also now fits.

The lug stud was 1 5/16". The new drum is from Rock Auto Raybestos 2611R.

Thank you all for taking the time to help me through this. I very much appreciate it. Onward to cab repair!