dana or 8 3/4 narrowing

Honestly you do not need the fixture.

get a good solid bar.
make your own pucks that fit snug inside ends of housing with a hole to fit the solid bar in.
i have a dummy center 741 chunk i also put in the center with pucks to keep the solid bar straight, but in reality you dont really need that center support.

measure alot.

I then take a 2 good size angle iron and clamp it to the housing. Then slide the new or used ends between the angle irons.
The angle iron keep the outside straight. The bar keeps the housing centered.

I also make a good chamfer where the two ends will meet and fill it full of weld.

I have done my own 8.75 and it has seen some slicks and about 500 foot lbs of torque.

I also have a narrowed dana 60 that i done just in case i pretzel the 8.75

I buy new axles from moser



True I made my pucks out of aluminum stock I had lying around easy to turn but I have a lathe cost me 15 bucks and you don't need a jig when you weld it up just weld a small amount and let it cool and a little common sense helps .when I narrow the dana 60 I cut the plug welds on the case and push the tubs out and cut them on the inside part of the tube then push them back in and reweld the plugs . that's if the ends don't need to be changed . if i'm converting a truck d 60 the ends need to be changed . easy peasy pumpkin pie .