Me too, and I've had several sets that were Mouse infested including a Truetone that had three inches of Apricot pits inside and had a couple transformers eaten but was no where near this dirty.
The set was in use at least till the early 80's so maybe it was just really dirty to start with.
It was really disgusting but surprisingly in good shape under all that whatever it was.
I thought it was just Mouse pee but it may have been a combination of Nicotine, Mouse pee and dirt. The rust left after wire brushing by hand was very light and simply went away with some Rustoleum.
I posted a more detailed account of the cleaning on this page:
http://www.antiqueradios.com/forums/...55415&start=20
I'm waiting on some Micas for the Sylvania so maybe after I get that finished I can get this on the bench and see what's what, it has a half dozen newer Orange Drops in it already, probably from the 1977 repair.
Side note, the original CRT was a 20CP4D, Electromagnetically focused, the tub ein it now is Electrostatically focused and there was a jumper wire from the focus pin to the Cathode or possibly G2. I don't know what number this tube is, it's not marked, possibly a 20GP4?