If I decide to put a 6 speed manual in my auto truck, what years should I look at and what years to stay away from. Also, will I have to get a new PCM because I am going from auto to manual. Any other "special" items that I would have to replace?

Thanks

 

I think 05 or 06 and later came with the G56, alum case Mercedes trans. 02 up to then carried the NV5600, heavy sob with cast iron case. Do you research to see which is right for you. 5600 would probably go in easier with a donor truck. Either needs crossmember replacement, different than auto or NV4500 mount. Transfer case needs at minimum input shaft swapped regardless of the manual in front of it.
If you can live with a check engine light you won't need to do a thing with the PCM, mine burnt out after about 5 years finally.