"Old Black is allegedly a 1953 GibsonLes Paul Goldtop. It has been customized quite considerably: after the guitar had been left at a guitar repair store, the original bridgepickup was replaced by a Gretsch Dynasonic single-coil pickup. Eventually a mini-humbucker pickup from a Gibson Firebird guitar replaced the Dynasonic. The neck pickup has always been the original P-90 pickup, but it is covered by a metal P-90 cover, most likely from a Gibson ES-330."
I can't find anything definitive, but from the sound of the recordings, I think maybe Jerry Reed used a 5E3 on things like Amos Moses and East Bound and Down. He was known to play a Peavey T-60 when he was doing electric.