72 Filler neck

Have a question about the filler neck.
The filler neck that was in my demon was not a 72 neck. Found a 72 but its about $250.00. My question is can you use a filler neck that is for 71 demon on a 72?
The only differance I see is about 71 having ECS, and is only $70.00. Does that affect anything? Thanks