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When painting the frame, we noticed a dent in the rear drive shaft tube, apparently the former owner ran the M37 aground on some rock. During an engine shake down drive around the block, we noticed the shaft creates a slight "arc" versus a straight line rotation. Its not a wobble that generates vibration - but we are crawling in 1st gear - its hard to tell what will happen at speed. Should we worry about this? Should we take it to a repair shop and have them cut/weld a new tube or replace?

I would take it to get looked at. Mine had a dent in it and I took it to a local driveline place and they rebalanced it and gave me an ok. Sometimes when these trucks were sold surplus they were loaded on flatbed trailers with a forklift and the driveshaft suffered bending. If the shaft is bent enough that you can see it you will have bad vibration for sure at any kind of RPM.

rixm37 is right on target here, if you can see the shaft is bent, trash it or get it re-tubed, you will have a vibration that will shake your teeth loose or worse no doubt. Just imagine the intense stress the u-joints will be feeling.

if u want orignal i wouldnt trash it, the spline on the slip joint is a discontinued design, not that something else could be used.

Thanks - you know how it is.... the list of "to do's" is already long enough, you're really not looking to add to it. I'll start looking for a replacement and keep building. Even if we can only drive around the block, we got to get this thing pulled back together because its taken over the house. Anyone have a source?

Send a PM to XM708-he's usually got odds and ends and might have a t/o drive shaft.
Gary

knattrass wrote:Thanks - you know how it is.... the list of "to do's" is already long enough, you're really not looking to add to it. I'll start looking for a replacement and keep building. Even if we can only drive around the block, we got to get this thing pulled back together because its taken over the house. Anyone have a source?

If the slip joint is good, I'd recommend re-tubing it at a local shop you trust. That way you can also get it balanced & should be good from now on. A shaft that has been balanced makes a much smoother truck.