I would look for a 1999.5-2001 E-350 SRW box van, like plumbers/moving companies/ or preferably an insulation company would use. It will have a Dana 70-2U FF axle in it with 10.5" ring gear. If you get it with parking brake cables attached, it will easily bolt in with NO modifications needed to spring or shock mounts. You can hang your factory calipers during swap and then bolt them on without opening/bleeding brake system. They are also @ 5" wider than your 60 so they track in line with front. These axles only came geared 3.55 or 4.10 in both open and limited slip. If you want to turn it into a 70HD, you can swap in 35 spline axle shafts and TrueTrac or other locker.