MikeL, if that Sorado cab with the 421s in it has a white X on on the back and some patches to the tolex on the front edge about badge high, have I got a story to tell you.
No, but tell the story anyway, you've got my curiosity going...
I got a Sorado cab in 1970 for $150 from Dennys Music in Portland Oregon. It was used at the Vortex festival (search "Vortex") which is why the back was marked with an X with what looked like white house paint. It got beat up on the trip back to the store after the festival because it rubbed on some other cabinet in the truck. I filled the divits with plastic wood and cut patches of tolex to cover the holes. You could barely see the patches. I installed Altec 421s. One of them stopped working and was reconed with a non-original kit. The aluminum dome was really thick, you couldn't dent it. Sold the cab in 1983.