If you can't find the TLN1251, you may find the TLN1250 "repeater Control Module".
It is the EXACT same board, same frequencies (1550 and 1450), same pinouts, etc, as the PL board, it is just labled different on the front. I think the only difference was the slot you plugged it into, and setting of any jumpers for the functions you want. I think the Repeater module is more common to find.
