I did more research and figured out the idler pulley by the alternator crosses to a Dayco 89006 which has an OD of 90 MM or 3.54 inches, a width of 30MM or 1.18 inches and a bearing ID of 17MM or .66 inches.
I downloaded the Dayco pulley guide PDF and found that a Dayco 89055 is 100 MM OD or 3.9...