Serpentine Belts

[tcat]

Going to replace my A/C and Alt belts, '05 Baja. Looked them up on Amazon and on Gates website. Both said to use:

K050350 (5PK891)
K040353 (4PK897)

Decided to look at the belts (after the fact), and they are marked 5PK887 and 4PK895. I have already ordered and received the Amazon/Gates belts.
Does anyone know which ones are correct or if it matters? I'm guessing the 891 is mm, so one is 4mm longer and one is 2mm longer, is there that much adjustment in the tensioner? And another odd thing... the length marked on the sleeves says 905mm and 912mm "OC". Just don't want to get into this to find I have the wrong belts.

[mowillie]

this is probably no help to you, but i did mine a couple months back. got them at Autozone.
AC - 355k4
Alt/PS - 350k4