Darren,
You revived a semi-aged thread but all good info and the only thing that likely is not current is prices that were posted in 2012, etc.
Welcome to the forum and congrats on the M18. It appears it's a 1975 vintage and sounds like a good deal.
Your M17 may be around the same time frame but without the serial #, it's a guess. The 17-3 ran from 1967 -1977, same as the M18-3.
ETA: Yes, pics are required.