loopyreed...you might find a date, on a sticker, on the end of the chassis....it will say TEST DATE. if it didn't fall off.....now...if that isn't on the end...you might see a red, grease pencil date on the underside of the amp between the wiring....they had one or the other...i doubt your amp went beyond 71...it might have been , lets say the end of the line amp and it was sold later in that year to clear the SUNN STOCK , if you will...so...pull your chassis out and look for the sticker or grease pen date....all of mine have one or the other...i would guess your amp is a 70's...it might of spilled over into 71 but no later....hartzell took over and did their own thing then....again....you have yourself a gem of a great sounding amp...now ! you do see on ebay from time to time sunn 6x12's and 6x10 cabs...you have to stay on top to snatch one up...and, be prepared to spend some money....look at it this way....we all piss money out the window on stupid stuff during the course of the year...if a cab comes up and the price is a little high, consider it your piss away money for the year. it's just your spending it all at once on a cab..their out there.....just wait for one to come on ebay and don't forget craigs list. check on that in the state you live in, and, the surrounding states so if one comes up, you can drive to pick it up....you'll get one, just not in the next 10 minutes...goodluck ..smiles Bob from mass....