From the TTORA Tech section for 95-04 Tacomas:
The axle code for your rig can be found on the manufacture's sticker located on the driver's side door jamb as follows:
First digit:
- A = 7.5" ring gear
- B = 8" ring gear
Next two digits:
- 01 = 3:42
- 02 = 3:58
- 03 = 4:10
- 04 = 4:56
- 05 = 3:15
- 06 = 3:91
- 07 = 4.30
Last digit:
- A = 2 Pinion, Open
- B = 4 Pinion, Open
- C = 2 Pinion OEM Limited Slip
some '98-00 models have shown a BO code of "???" on the door plate; so far this turns out to be a 3.91 gear ratio, at least for the 5sp. RZN171L-CRPDKAB with factory 31s/265s should be 4.56 with the AT.
Edit by Ed Quinones on 10-7-05: I used to own a 99 Prerunner ext cab 2.7L with auto tranny and gear code of B07A. It came from the factory with a 4.56 gear ratio.