if you have gen 3 4x4, 2.7 AT with 31" OE tires you should have 4.56s
5spds got 4.30s
some gen 2 trucks got the same but not all.
the change was to compensate for the larger tires, 31s or 265s.
earlier models came stock with 3.58s and 225 size tires. Then came 235s and either 4.10 or 3.91 depending on tranny. Dealers started swapping tires to 265s even with gears meant for smaller tires ( I think the factory did this as well, stupid move). Toyota finally wised up and lowered the ratios for the larger tires. All this for 2.7s only. All v6s got either 3.91 or 4.10s (with one early exception) and all v6 TRDs got 4.10s. IMO, Toyota should have offered a 4.30 ratio for v6 AT TRDs with 31s.