I did some more fiddling and I think I made some progress. There is no shims for the planet gears and upon further inspection there needs to be. You can't get good gear lash by using the supplied shims on the side gears alone so I made some out of washers for the other gears. I had to assemble and disassemble them a few times each, carefully filing the washers each time. Seems to be much better now as it towed the gen-set from one end of the shop to the other with no complaints even while turning left and right.
Here's what breaks...
Here's what I'm hoping fixed it...
and a couple pictures of my trucks together....
Thanks for lookin