My boss has Case/NH, Two CAT programs, Navistar and about ten other diesel diagnostics on two computers.
He paid about 5g usd for each major brand including JD. Which is now unused because NH tractors get the best support in the ag area. It was commercially available via a biz in the big city nearby.
And I know what Muddy says. Fix the engine and clutch, patch the radiator and the hydrogizmo trans is still wonky, the brakes not as good as before.
And he spend 1/3 the price of a replacement for that.
The limits of where to fix and when to scrap the old one are fuzzy. Usually any unsupported drivetrains are the fatal shot.