I was talking to a friend of mine about selling my amp - mesa trip rec.
I asked him if there was a difference between the 5150 and the 6505 and he said there wasn't any difference at all? not even in the schematic or anything.
I've got a block letter, and other than being cantankerous and old and having different valves; it really sounds no different to a signature; sure you have to dial the pots slightly differently for EXACTLY the same sound, but thats more aging components and valve difference...
also; check out Peaveys own Elmuchos talking about this urban legend nonsense that online forums has perpetrated