Whoa, a little more digging netted a good find. It was tire recycling day at "Casa de Bachelor", 52 if I remember correctly:
And then an early shot of my trailer frame before decking went down. Tubing is all 2X3 rectangle except rear is 4X2. Some 1.5 squ. in there too, painted silver to match.
I sure miss the looks I used to get towing the sandrail with my wagon.