Originally Posted by 99F150
Sounds like the axle seals are leaking causing the brake shoes to get soaked in oil causing the shudder.
Does the rear end whine or clunk? If not it may be able to be fixed by replacing axle seals and maybe new bearings.
dan
I concour. It sounds like seals and bearings are gone. This mechanic did he elaborate more. As if the gears were wore, was something broken and further damaged the casing or other gears. Most cases are bearings and seals and the gears still can be in pretty decent shape. If its bearings and seal, these can be gotten. If it is the pinion and drive gear, you still can replace them, but very expensive.
If it is those, look for another econoline with a rearaxle in and see if you can change it. The other is look for a mid size Comet, Falcon, Fairlane from the early 60's, for the gears in them would be the size to fit your carrier.
If you know someone else that does differentials, maybe see if he can have a boo at it and give his opinion.