ASSISTANCE WITH MOTOROLA GM300 REPEATER

There are some mods published (on Batlabs, and in an old edition of
M.R.T.) which have some simple mods for turning a pair of Motorola
MAXTRAC mobiles into a basic repeater. Receive activity on one radio
keys the PTT on the other radio, and vice versa.

I am attempting to do this with a pair of GM300s'. These are
supposedly "the same" radio but the board on the GM300 is signficantly
different than the MAXTRAC described in the published material.

Can anyone provide some specifics on performing this mod on the GM300?
I hear it can all be done through the aux. I/O ports on the rear of
the radio.

Thanks!
Dan (remove the NOSMAPM below)