Universal Colt

1911 Officer replacement parts?

I own a Rock Island Armory 1911A1. It is the same as a Colt 1911 Officer model with the 3.5″ barrel. I want to do some custom work to it such as replacing the trigger, hammer and sear, magazine release button, slide catch/release, and all the pins. My question is are parts like those universal for all 1911′s or do they have to be specifically made for officer models? I have been looking for parts online and have not found any distinction really. If you know the best place to order parts that would also help me a lot.

the parts are universal except for short 1911 versions, gun forums and gunbroker.com all have parts

Colt Starting IV – Advanced ground work