differential narrowing jig

You don't need ANY of that stuff. NONE of it. By the time you are going back together with it, you will have figured out your new axle length and gotten the new axles. You'll HAVE the new ends. Figuring out WHERE to cut the housing is simple math. I'm not even goin there. Easy peasy. Once you're ready to assemble and weld the new ends on, mock it up loosely. With the ends in place and the axles and bearings installed. I take for granted at this point, you'll have the housing and ends prepped and angled to weld. The ends weld on with the horizontal center line of the ends parallel with the pinion center line. Easy. Using your hands you can feel for what I call the "sweet spot. That's where there is no binding whatsoever with the axle bearing. That's ALL you're after. That's ALL that 650 dollar tool does for you, is get the housing ends placed correctly so the bearings don't bind. Since the housing might be bent or warped a little right from the factory, just welding them on with the outer edges lined up ain't good enough. You need a reference coming off the differential carrier. What better tool to use than the carrier and axles themselves? Simply get the ends in the right place, buzz two points 180* from each other. That way, if you need to you can take a ball peen hammer and smack the end in a direction that frees it up the best. Once you got that down, weld er down. It's really THAT simple. I've done several like that and never had a problem. Not one.