In a message dated 10/7/98 5:44:30 PM Eastern Daylight Time, Jweir at worldnet.att.net writes: > Can anyone tell me if all the Z (4.3) engine coded vehicles in 91 used > the 7747.. Hi Jason... The 1991 4.3 turbo (Vin code Z) used a 7749 ECM. I think most, if not all non-turbo were your 7747 though.. HTH Mike V