'97 f150 v-6 throwout bearing
 

I'm sticking in a new throwout bearing and it came with a blue plastic collar? The old bearing didn't have the plastic collar so I took it off. Should I have left it on and would it have fit? The box said read the instructions, there weren't any. The Haynes book doesn't show a plastic collar. What should I do? collar or no collar? bl2009