Door board would be at the top of my list and make sure they all have rev. 23 generic software. There's a good chance at some point you will have intermittent iserial comm flts (20/3064) and no door comm with rev. 22, better to load the 23 generic before you have a problem.
Next likely for problems would probably be HN and HNB cards, followed by selector TSA and TSM. Further down the list is the IOD and CPUA and I have only had to replace one CWI card. There are also some s24 I/O cards in the COP and breakout boards at the hall stations.
Depending on how many units you got and the level of service you want to provide, it would be nice to have one of each on hand but wouldn't that be nice for any equipment you have on service.
I would make sure there is a USB stick in every controller and I would do a fresh UDLS to backup the Generic and Job image software. It is an easy step that can save you a lot of time if you completely loose a CPUA card.
All the boards are interchangeable with all TAC 32s as far as I know except for HN cards that do need to be the same version but these are only the intermediate floors as the terminal floors have HNB cards that you can load firmware in those so the versions of both match.
