I am in the process of making my 46 1 1/2 ton a daily driver. I live in the mountains and generally the freeway is the only way to get anywhere (especially in winter). The 6.13 gears in my diff top me out at 45mph. I've done 55 but it's not sustainable. My replacement rear axle is a Dana 70HD, factory disk brakes out of a Chevy based 2 ton motor home. The lug pattern is the same but the studs are 5/8" instead of 9/16", the hub pilot is larger than the period correct wheels and the wheel mounting surface is 1/2" narrower than stock. All workable problems for me and to my knowledge this is the closest axle to "working" without going custom. The stock 46 drums seemed to need to be adjusted every 100 miles to keep the pedal where I want.
