The 1998 Ford F-150 had three transmissions available with this truck. Manual transmissions only made up 20 percent of all the transmissions available, but are the hardest to identify. Made by Mazda, the automatic transmissions look very much alike with small differences in all light-duty trucks, although the gearing is entirely different depending on engine size and other factors. The smaller the engine, the lower the gearing and the need for a lighter-duty transmission, making this transmission unsuitable for a larger engine. This is where care must be taken since the tags are usually missing that describe the gearing. Without these tags it is difficult to determine to which engine the transmission is mates. The 4R70W is the standard transmission with the E04D and 4AOD as options.
Look at the label on the driver's door jamb. A "U" is the designation for a 4R70W four-speed automatic transmission rated at "70" (70 times 10 = 700) foot-pounds of torque. If the designation is an "E" it is the optional E04D, a four speed automatic transmission with overdrive.
Count the number of bolts in the transmission pan. If there are 20 bolts in the pan, it is a 4AOD. Less bolts, it is a 4R70W.
Identify the manual transmission by calling the dealer and he will give you the exact gear ratio standard with the truck. The truck's computer is set up for a specific ratio, so it is wise to stay with the original ratio. If a tag happens to remain on the transmission, record this number and call the dealer for the appropriate parts or identification so you can purchase the appropriate parts. The only other method is to remove the transmission and tear it apart to count the teeth on the gears.
