On manual transmissions, the identification number is located on a plate attached to the main transmission case. On the plate you find the assigned part number, serial number and bar code used for inventory purposes.
B2200 Pick-up models use the M4M-D 4-speed and M5M-D 5-speed transmissions. They are essentially the same unit geared differently.
B2600 Pick-up and MPV models use the R5M-D (R5MX-D w/ 4x4) 5-speed transmission.
The Navajo uses the M5OD 5-speed transmission.