Transmission code W
 

Can someone confirm this code for me Truck is a 91 F-250 4x4 with a 5 spd. Previous owner has no idea what tranny it has exactly . Had one of my buddies look it over he,s pretty sure its a zf. Hes not exacly a ford guy, Also im pretty new also newest ford ive ever owned. Any help would be apreciated, just hate not knowing what my truck has.

In 1991 they did not have a "W".

But an "M" was a 5 Speed M.T. w/OD Mazda.
A "Z" was the ZF.

Being an F-250 it should be a ZF.

ODE YEAR SPEED DESCRIPTION NAME MODEL
A 90 4 Manual New Process 435
B 90 4 Overdrive Clark
B 94 4 Auto E4OD
B 03 5 Automatic Torq Shift
C 90/ 5 Heavy Duty O/D - M5HD ZF Close Ratio
D 90/94 5 Manual (O/D) MMC
E 90/ 4 Auto O/D E4OD/, 4R100
F 90/93 4 Manual Warner T18
G 90/96 3 C6 Automatic Ford
K 90 3 C6 Automatic Ford
L 96/02 4 Auto O/D A4LDE, AX4S
M 90/ 5 Manual O/D Mazda (R2) M5R2-C, M5R2-C
M 96/02 5 Manual Mazda (R2) M5R1, M50D
M 91 5 Manual HT Mitsubishi/MMC
N 96/02 4 Automatic 4F5ON
P 96/02 4 Manual Warner T19
P 93/ 4 AOD Nissan 4F20E, RL420a
S 90 5 Manual
T 90/ 4 Automatic Ford F10D, AOD, T5OD,A4LD/4R44E, A4LDE
U 93/ 4 Automatic O/D AODEW/, 4R70W
W 90/ 5 Heavy Duty O/D ZF Wide Ratio - M5HD-W
Z 90/94 5 Manual New Process
5 90 5 Manual (O/D) TK
5 90 5 Manual

Question was answered on another thread here, Btw it is a W and it is a 91 (yes its a zf also) Thanks For the list Purple saved it to notepad, Im late model ford impaired lol.