Strange or MW thru bolt aluminum case. The strange ultra cases are nice, but so is anything MW, and you can get either that will take 9-1/2 gear. 3.81 bore. Taper/ball pinion support. 40 spline axles. Spool can be either aluminum or steel, steel will last longer.
Tons of places sell fab housings, or Rhodes sells one you can weld up yourself. Go 3.25 or 3.5" tube, and Ford or symmetric ends.
