Ampeg Jet D20. New grounded cord, new can capacitor, new rectifier diodes, newer ampeg ceramic speaker, new 7591 electro Harmonics power tubes, and original ampeg 6BK11 compactron tubes for preamp, tremolo, and phase inversion. Lots of dark girth, but no sag in this bad boy. One on/off pot. for the speed of the swampy tremolo, a bass/treble tone pot. and a volume pot, for the controls. Two inputs an on/off toggle and a blue jeweled pilot light finish the control panel. A new blue leather handle has been added and the 60ish year old blue checkerboard tolex is in great condition. Made in Linden NJ with a serial number of #019400, their code is YMMNNN so maybe you can figure if it's a 60 or 61, cause I know there isn't a 19th month on any calendar. I'm thinking Sept 61 400th amp, maybe.