That's a solid looking truck.
Not too long ago I came home from work and my 65 C10 had had a massive blowout on one tire. It was just sitting in the carport. I had been under it many times wihout jackstands, but now I don't get under there without them in place and I would advise you to do the same. Don't trust the tires
yeah these tires have deep cracks and are pretty old. I only had a pair of stands and I don't trust the other tires to hold the weight even though they are still holding air. I debated getting some cheap tires for now just to use as rollers but I figure just get a decent set now that I can (hopefully) drive around on once it's running again.
I was under my '65 a few months ago and got to looking at the tires, and immediately went and got jack stands. My thinking was that I was done for if a tire decided to give out while I was under there. They're still holding air, but when I get under that truck, because the tires are old, I always put jackstands under before I begin work.
Yikes. I know it's probably unlikely to happen without warning but I wasn't willing to risk it either.