In searching the 60 in the 1990-2004 e250/350 is a offset rear axle with the pinion shifted to the passenger side.
Unfortunately not to common to other axle option in the E250/350s
I will search more I can pick up either van type for 300-500 dollars for whole van not running. But not local to me to measure and verify center pinon, actual 60 (not 61 or 70), actual width which varies. But can add it back in as another path to look at again.
