KT76A Replacement for KT78A

Has anyone replaced a King KT78A with a King KT76A or KT76C? My KT78A is weak and I am considering the uAvionics Tail Beacon for ADS-B out. So I need my transponder to be good. The KT76A or C appears to be a strong transponder with 250 watts output up to 30,000 feet.

So is the KT76A truly a plug-n-play replacement for the KT78A? My reading says they are interchangeable with no wiring changes. But what does that mean? Is there a setting or something that matches the transponder to the encoder? Is it something I could do without an avionics tech?

thanks

Its been several years since I worked on them but the only difference between a KT-76A and a KT-78A is the cavity (the tube that xmits). And that was the difference, xmit power out. (125W vs. 250W) They are interchangeable but when you remove one and install the other you are required to comply with 91.413 which is the xponder check which can only be done by a repair station. Not sure about the C model.

Jay