Hi all. I have two heavy sixers in boxes that I'm debating which one to keep. One is the traditional 1977 version with the chess head box. The unit is in good condition, works great, and has a lower 'E' serial number. The box is in just ok shape, and is probably a 5/6 out of 10.

The second heavy sixer is one of the last made, is an 'M' coded serial number, and comes in the Revision 'B' box without the chess head. The unit is in great working condition, and the box is a little nicer, scoring a 7/8 out of 10. that said, the housing seems to be a bit rare for a heavy sixer, as it has the channel select hole with switch inside on the bottom of the unit by the venting ports. I have not seen one like that, and thought the rarity might trump a run of the mill, 1977 heavy sixer. The internals are a little different as well.

Any opinions or comments?