Hello Joe Bob, I have a Case 70+4 trencher and I'm having the same problem of not finding any manuals for it! However, you are luckier as there is a service manual and a couple parts manuals for your trencher for sale on Ebay right now. They are a bit pricey, $169.00 for the sevice manual and $111.00-$159.00 for parts manuals, but they are there for the taking. I hope this helps you.
Best wishes,
Agman55