Used RCMs require a trip to DJ's before use - only cause they ALL fail eventually. Leaving your garage in a Crossfire without a spare RCM in the trunk is like leaving home without your wallet.

I'd ship mine to DJ, then also order a NEW one. That is what I did. My new one fixed the car and the rebuilt one from DJ is my spare. This is how you keep yourself from being stranded without warning.

RCMs are generic and they plug in like plugging a lamp into an outlet - super simple, no tools needed.