EDIT 2014/07/08: These are for sale, contact me if interested(johnbrier at the popular google mail service)
I bought a couple of these on eBay around 2000 with the intentions of modifying them to work on 6 meters but never did as I was too intimidated on the work required to complete the mod. I hope to do it still, sometime sooner.
All GE Mastr IIs have a combination number which describes the features of the particular Mastr II:. The two I have have the following combo numbers: MX64KFU33A
The meaning is described at this site: http://www.nhrc.net/mastr2/combination.php
For mine you can see I have:
M - Standard Mechanical package
X - 12 VDC
6 - 41-80 Watts
4 - 20 KHz channel spacing
K - 8 Frequencies
F - 4-Freq. Xmit. 4-Freq. Rec.
U - has Channel Guard option
33 - 42-50 MHz operation
A - ± 5 PPM (± .0005%) oscillator stability
I read that it is best to make sure they work on their intended frequencies first, before modifying them to work on 6 meters. However, I don't even know how to figure out what frequency mine are supposed to operate on. Currently, I have only control head cables and a microphone but no control head so I guess I'd have to locate a control head or build some sort of control head first. Looks like I would also need to buy a frequency counter to align it as well. Any thoughts or advice is appreciated.
more pics are here: