If you search for the thread on this, there is a place in the new England area that sells the cores. I am talking about the round cores. I did my own repair because the local rad shop was no help and I didn't want to spend the money for a new one.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!