@JeffK10America,
Yeah, that's what I was saying above that my original brass/copper rad. lasted decades. I had to get it boiled out every once and awhile, but once fixed it would be a long time before it needed to get anything else done to it. And I always used good anti-freeze to. Then the core finally went out from corrosion and I looked into getting it cored and start from scratch. The shop wanted $250. Well, I found a new one on line for $250. But I also looked up one of those aluminum ones with the plastic tanks. I could not find a rad. as thick as mine and looked for a month.
I even went way off my year truck and was looking at Pontiac's, Oldmobile's, and Buick's, and Cadillac's. But that was after I had already looked at all the year trucks from '73 to '89 in C20, C30, G10 to G30, then P10 to P30 R's, all the K's '73 to '89 and I mean all engine sizes to. And all I could find in aluminum with plastic tank rad.'s was 1" core, a single core replacement. I called radiator manufactures and asked if they would custom build me a three core alum. rad with a plastic tank. They said, no they would have to make a special mold for it and it would end up being to expensive.
Then finally I found a three core radiator for a late '80's big block Cadillac but it had a oil cooler in it besides the trans. cooler and I didn't want that. I think the problem was more the specific size I wanted it in, 29" wide by 19" tall. Which is pretty much standard. So it was either I go back and cough up the $250 and get a new brass/copper one, or get one of those all aluminum ones custom cars have. I looked them up and found a three core for my truck for $158! Well, I got one, and I really like it a lot. I swore I'd never get one of those but price was the deciding factor.