I have built a few models now, but they have always been straight out of the box builds, modifying only what I might add or remove in the field (or in one case, removing some bustle racks I broke ). I have never converted one vehicle to another type or variation, so I thought I would pick an easy one to start.
I want to covert an M270 MLRS to a M4 C2V (Command and Control Vehicle). I thought this would be easy, and was wondering what any of you think, especially those who have built the MLRS kits.

M270 MLRS
http://www.globalsecurity.org/military/systems/ground/m270-pics.htm

M4 C2V
http://www.globalsecurity.org/military/systems/ground/c2v-pics.htm

I dont believe there is an M4 kit available so correct me if I am wrong. Other than having to scratchbuild the massive antenna at the rear, what else do you guys notice that I would have to change or add/remove?

You are correct that there is no M4 C2V model. You would have to scratch much more than the antenna mast though. The C2V has a totally different rear box in place of the standard MLRS LLM (Loader-Launcher Module) box on the back. It is longer and taller and has a totally different shape to the top angles. It also comes over the engine intake area with a generator section and has access panels all over it. The only thing they share is the basic M270 carrier vehicle. Take a closer look and you will see the differences. Good luck with it.

I wasnt sure all of the extras I had to add, thanks for the heads up. I just realized they shared the same basic shape, and figured the base model of the MLRS would give me a good starting point to build off of.