There is a need for a how-to guide on repairing and upgrading TMCC electronics, but none has been written or made available to the consumer. The situation is complicated by the many variations of TMCC: Modular and non-Modular boards, Standard and Cruise boards, 3rd party licensee versions from Digital Dynamics, TrainAmerica Studios, Electric RR Co, and K-line, 8 versions of Railsounds boards, and multiple motherboard configurations. I actually compiled information from the forum on TMCC electronics into an organized Guide to TMCC, but the forum moderators declined to allow me to publish it on the forum since the photos of the TMCC electronics were not my original work (I understand their concerns, since they had to pay out damages for a photo copyright violation a couple years ago).
Useful information on troubleshooting and upgrading TMCC electronics is scattered through this forum. Much of what I have learned on the subject came from here. The other really useful source is the "Chronicles of Norm" series on YouTube (search for Norm's Trains). Norm knows TMCC electronics like the back of his hand, and shares his "best practices" as he upgrades electronics in his locomotives.
Back to your original question, yes, there is considerable interchangeability of TMCC electronics. But unfortunately, Lionel suddenly and without explanation pulled all the TMCC and some early Legacy electronics from their parts site. At this point, it is likely that we will find Jimmy Hoffa before we find this treasure trove of parts. Currently, Electric Railroad Co is the most reliable supplier of boards to upgrade and repair TMCC locomotives. Some boards show up on eBay or at train shows as well.
Don't hesitate to post a repair or upgrade question to the forum. The electronics gurus here are very willing to help. Many times they will give you step by step instructions and parts numbers and photos of everything you need. To get the best response, make sure you list the locomotive product number and post photos with your question.
Bob