380sl idler pulley replacement

[mbboy]

Seems like the bearing on the AC idler pulley of my 81 380sl is going. So I'd like to replace it. However, some vendors list the Beck Arnly bearing as 051-3954 and others list it as 051-3860. So, I was wondering if any of you guys know which one I should get?

Also, the EPC lists the pulley screw as PN 1159900219, which is now a stretch screw. So I was wondering if the original was also a stretch screw and, if not, whether it can be reused.

Thanks for the info.