Anybody have a good source for parts on these motors (477)? I've got a '67 C-850 grain truck w/ an Allison Selectomatic (or something like that) tranny. The rig is rated at 39,000#. Shifts hard but pull is just pathetic - empty! I should say that this was a mouse condo for a few years but is now back in action - sort of. Thanks for any help.