What Frame is This?

[Mr. Chevrolet]

Hey guys!

I have a '53 Chevy 5-Window truck that the previous owner swapped frames on. He was an elderly man, who I'm sad to say died of cancer not 2 weeks after I purchased the truck from him. With him went a lot of the details on what mods he did to the truck. When I asked his son if he had any idea what the donor frame was, all he could say was "I don't really know, I think it might have been a '79 C10?" Not exactly helpful.

So here I am! I crawled under the truck and took these pics of the side of the frame, is there any way I can get any info off of these, or am I going to have to suck it up and somehow get the VIN stamp off the top frame rail?

This is what it says:

(S) 8 169
14007646




Thanks for the help in advanced!