Based on our two trucks, the M139 and the M812A1 use the same wheels, which have such a deep off-set, that they will not boltup right to a standard truck axle, front or rear.
The front axles on the bridge trucks are the same hub to hub length, but have a thick spacer so the deep dish wheel can boltup without hitting the steering arm. The rear axles are longer than standard trucks and have a spacer on the hub to further space out the duals. They also are spaced apart wider(longer) than the standard duals so the 1400x20 tires have at least the same or greater spacing between the tire treads.
Somewhere on here are pictures of our trucks that may show this better. It's too bad that the bridge truck wheels don't work, as there seems to be a lot of them around. Anyone ever look into cutting out the centers and rewelding a new correct offset center back in? Between our three trucks we've got 32 wheels to try it out on. Shipping would be a problem, as they must weigh at least 100# with the ring!!
