Re: Rear axle moving left/right
 

Yup 3A is 3100 short box pickup. I probably hit B rather than A when I typed it.

If the 56K-------- matches the rest of the serial number on the door post life should be good. The factory shows no frame numbers and that number may have been to make sure that chassis gets mated with that cab at the factory. They started adding a lot more options for the rolling chassis in 55.2 than we have on the AD trucks. 48/53 you got a 216, either three or 4 speed and could get a heavy duty clutch and that was it outside of overload springs for the rear and tire size.