1991 F-Series Drivetrain Info and Codes

Rear Axle Codes
    Code    Manufacturer   Capacity(lb/kg)    Ratio
F-150, F-250, F-350, & F-Super Duty with Conventional



F-150, F-250, & F-350 with Limited Slip



Transmission Codes
    Code       Manufacturer        Description       Model     Gear Ratios (R : 1,2,3,4,5,...)
     T            Ford             Auto 4Spd OD       AOD


Engine Line-Up and Specs. 
Engine Displacement   4.9L/300       5.0L/302       5.8L/351       7.5L/460       7.3L/445
Type and # of cyl.    Gasoline, I-6  Gasoline, V-8  Gasoline, V-8  Gasoline, V-8  Diesel, V-8
Fuel System           Multiport EFI  Multiport EFI  Multiport EFI  Multiport EFI  Mechanical FI
Bore and Stroke       4.00 x 3.98    4.00 x 3.00    4.00 x 3.50    4.36 x 3.85    4.11 x 4.18
Compression ratio     8.8:1          9.0:1          8.8:1          8.5:1          21.5:1
SAE net horsepower    150 @ 3400     185 @ 3800     200 @ 4000     230 @ 3600     180 @ 3300
Net torque (lbs.ft.)  260 @ 2000     270 @ 2400     300 @ 2800     390 @ 2200     345 @ 1400
Manufacturer          Ford           Ford           Ford           Ford           Navistar
VIN Code (8th digit)  ?              ?              ?              ?              ?