Ok, truck is a 1994 Crew Cab with a rebuilt 1996 460 and E4OD. I don't remember what the part is, but it's a lock-up something in the tranny. I thought of this today, could this lock-up thing not be doing what it's supposed to be doing, and thus I have BELOW the characteristic terrible gas mileage (I get about 7-8 highway) -myers