I've seen NPD's and Virginia's belts but I am a bit confused as to which ones to order. NPD lists an alternator belt with A/C, C4AE-8620-A. The power steering belt is listed as power steering with A/C, C60E-8620-D. The A/C belt listed is C4ZE-8620-B. I thought the A/C belt also hit the smog pump pulley. They do not list a A/C with smog belt for 66. Mustangs Unlimited shows an alternator belt with TE, and a P/S belt with A/C. I think they following is correct for my motor: alternator belt hits alternator, water pump and lower pulley. 15/32"x 40". Power steering belt hits P/S pump, water pump and bottom pulleys. 15/32" x 49.75". A/C belt hits A/C compressor, air pump and bottom pulleys. 1/2" x 61.25".