idler size ?

[Ryan]

3" is the correct size for your B-112. Ryan

[Bunky]

hello I had posted earlier on my B112 with PTO problems i got it working but i think someone has changed the idler I also have a 3210V and the idler on that is 3 1/2 inches and the one on the B112 is 3" can some one tell me what the correct size????????