DWRay
If you want a wild "GUESTIMATE" here it is
Early to mid '60's. You don't see many BALBOA's, and I never could figure out why. They are great bows.
As far as being the same bow as the Martin MAMBA, I don't think so. The Martin MAMBA is a continuation of the Howatt MAMBA, another great bow. I would venture to say that the MAMBA, the DIABLO, and the HI SPeed (even maybe the HUNTER) were all very semilar with the main difference being the AMO length. I think the BALBOA was short lived and they changed the length of the MAMBA to whatever the BALBOA was. I may be wrong here but I think the MAMBA was the longest running name for Damon Howat. You see some older models looking like '50's bows, and you still see the MAMBA carried on into the Martin line.
In any case, with Bear and Ben Pearson haveing better name recognition and market share, I don't think Damon Howatt got the respect they deserved back in the '60's. Althought they were not as well known, or as popular, I feel that they make one of the best quality bows of the era, as good as Bear (if not better) and certainly better than Ben Pearson.
You have a real keeper there. I have several Damon Howatts and am pretty much satisfied with what I have; however, I would love to have a BALBOA simply because they are so uncommon.
At 65#, yours would be a bit stout for me.