I think all these twin I beam Econolines wander a bit. I had the ball joints replaced and the toe was off. It was like riding a wild animal, it would dart left and right. Toe was re-adjusted, and it still wandered. That is when I replaced the link that goes from the arm on the steering box to the long rod that connects the 2 tie rod ends ( I'm not up to date on all the suspension part names). That joint would deflect 1/4" before moving the long center rod. It is tough to find someone that really understands the twin I beams. I had it to a Ford Dealer (car side) and another alignment shop. Finally went to an RV place that dealt with van based campers and found someone willing to really look at it. They also recommend D range tires or keeping the pressure up.

My old van has been a champ. 190k+ on it, still pulling boats and a horse trailer. We took it to Ft. Lauderdale with 6 kids in it over Memorial day, willing to cruise all day at 80 mph. The old 5.8's are tough.

I sold the 140 about 5 years ago. It bent a rod, and I was going to swap in an '87 603, but had just got a new job and ran out of time. It was also starting to have electrical problems and the AC needed a recharge ( evaporator?). I've had an Infiniti I-35 since. Put 195K on it and the only issue has been a crack in the radiator. Would love to get back into a diesel since my commute is 150 miles a day, mostly at 75mph on the highway. I just sent an email to a guy selling an '87 190D yesterday, might be a fun toy / commuter.

Good luck with the van you are working on and let me know if you want a copy of that Truck Manual CD.

Chuck