There are two belts on my V6 Camry. One heads towards the rear and runs the power steering. This has 4 ribs. The belt I am concerned with is up front and has 6 ribs. It is tensioned by the alternator itself, there is no idler.
I purchase a replacement belt online for $12 -- a Bando 6PK940. Some sellers call this a serpentine belt, but it really isn't.
Two bolts need to be loosened on the alternator. One is the pivot bolt, the other a clamp on the bolt that adjusts the tension. Then the tension bolt can be turned to drop the alternator so that the belt can be slipped on. Then adjust the same bolt for proper tension, tighten the other two and you are done.
The belt I have is too short. I measure it at 37.5 inches, which is 952 mm (the 940 in the part number is probably a 940mm dimension).
That's what I get for letting the Amazon web page select parts for me. The rub I think is that there are two belt lengths at this location. One if you have A/C (as I do) and one if you don't. The one if you have A/C is 105mm longer (about 4 inches). So, off I go to O'Reilly (they sell Gates belts versus Autozone where you get "Duralast" - whatever that is). Same price. An hour later, I have the proper belt (Gates 6PK1036 K060407). No doubt the "1036" indicates the length in mm. The package says 13/16 by 41-3/8 inch (20mm by 1051mm). Whatever the case, it fits! Made in Mexico.
You need a 14mm socket for the pivot bolt, and a 12mm for the two tensioner bolts. I also removed a box labeled "fuse and relay" that was in the way to the left of the radiator. Remove two 10mm bolts and this can be shoved out of the way.
Tom's Camry pages / tom@mmto.org