You might try I think the company is called comspec.  I use to buy tone
boards from them when I was doing commercial stuff.  They won't have the
exact replacement, but if you're wanting one specific tone, they make a
very small board that can be set and put anywhere inside the radio.  It
just has gnd, audio, and b plus.  Just feed the audio into the xmit mike
circuit somewhere.
73s
Butch Bussen
wa0vjr