Hi,
I just went through the same thing when I thought I found a good deal at a local shop. I bought a pre 82 for 65. and a 28 gauge kit for 55. but the problem was that the caliber kits are specific to the versions made. If you put the units side by side the units are almost identical. I had to return the press and buy a new one.
Look on Mec's website and download the manuals for the respective model you have.
If it has a flat base plate and a silver sticker with the S/N then its a pre 82.
If it has a slightly raised base plate and doesn't say mk.5 then its a 82-85
If it the base plate say's mk5 then it was after 85.
I can't get you any closer than that. Doesn't really matter as parts are easily available and the press will still out live your grandchildren.
Paul
