need age/size for Goettl HP

My local Goettl office let me down yesterday. Apparently, there is ONE person that works there that can decipher their own date code.
Can someone help me with the manufacture date and size here?
Goettl: GBHP361 SN: 417
(I think it’s a 3 ton)

I plan to go to Bookman’s and buy a Preston’s manual so I don’t have to rely on others. :slight_smile:
BTW, is that a good HVAC book for the purpose of finding manufacture dates?


The manufacturer FINALLY got back to me. Just fyi, a 3 ton, manufactured in 1984. Don’t ask me how they get that from the serial number?!?!
Thanks for your time.

The 36 in model number gives the tonnage and if the sn is correct although I haven’t seen one with just 3 numbers the first number sometimes represents the year