Hello,
On the existing system, what breakout boards are being used with the 7761 DSPMC? This will help us determine the compatibility.
If you're not certain about the breakout boards, you can take pictures and post them over here so we can take a look.
Depending on what parts are currently present on your machine, you may need to perform some rewiring by consulting the pin layouts for the 7762 DSPMC.
The software configuration will also need reviewing since the 7762 Mach3 plugin has been updated several times.
Let me know what parts are present, and I'll let you know what can be done.
-Marc
Vital System Inc.