If you're working with GE radios, here's some links that might be of help or interest:
Information on wiring a KPC-3 TNC to a Phoenix radio, and plans for the GE 4EX22A10 hand programmer. FYI, the computer-based X2212 programmer was built out of hatred of the hand programmer.
Heaps of information, including the conversion of Phoenix and Delta VHF radios to 9600 baud, attaching TNC's, building J-pole antennas and tons of other fun stuff.
Plenty of information on converting/running Delta radios on 10M and 6M, and building a control head for these radios. This person also has a heap of Delta S radios for sale.
The GE-User mailing list - has over 200 members, and an archive full of useful GE information.
Hall Electronics - has loads of GE/Ericsson documents, surplus GE parts, and tons more.