My current plan is to get an 8.8 out of a Crown Vic. The later ones have 31 spline axles already, drawing a blank on the cutoff right now. Maybe ‘01? They have 3” axle tubes instead of the 2.875” on the Mustang and 3.25” on the Explorer. Then I am going to get some axle ends from Moser that allow ‘05+ Mustang brakes to bolt on and use pressed on 9” axle bearings so no c-clips.
Not the cheapest way, but maybe cheaper than an 8.75”. I think I can build it for less than an 8.75” chuck.
Just some thoughts.