Fender Reverb ,Reverb Unit,Tube,Black Face, first 1966, EX+

Reverb Unit Dating 6G15 (brown, blonde, blackface)
 R00100 to R00900 - 1961
 R00900 to R02600 - 1962
 R02600 to R04800 - 1963
 R04800 to R07400 - 1964
 R07400 to R09800 - 1965
 R09800 to R11000 - 1966