Notice local govt accepting bids for a 1971 CAT 140 motor grader, I am wondering if its to old to purchase. My concern is the replacement of parts, CAT does not stock. It's in decent shape has been used continously, they upgraded is a newer CAT 120G.
I think you'll be fine. Cat does a good job on parts for older machines. There might be a small delay in getting them but they aren't obsolete or NLA. Some of them might even be Cat Classic which is cheaper, not necessarily made by Cat but built to their specs. Call up the local dealer and throw a few parts requests at them and see what they come back with.
I can get parts for my 1959 Cat track loader and my 1957 Cat D4 dozer at the Cat dealer. About half the time they're in stock at the dealer and the other half it's sitting in the local warehouse which delivers the next business day.
Should be pretty good on parts
You shouldn't have any trouble getting parts for that machine I can still get some parts for my no12 grader which is a 52 model like d9 and junkyard said it might have to be classic parts also if they can't find any parts in their regular system have them look in their legacy program that's where they have to look for parts for my machine