In some cases- it followed the tire sizing-
If a vehicle were ordered from the factory with a tire upgrade- say from 225 to 265- it received lower gearing-
Also, certain 4cyl Tacomas actually had lower geared 4.56 from the factory- probably 4cyl w/ auto tranny
The fact is Prerunner/4wd Tacomas came with anything from 3.58, 3.91, 4.10, 4.30 & 4.56....
I don't know the magic combination......
Good luck with the search-
I have a spare 4.30 rear diff but its not for sale unless the price is right-
Its a back up diff since I have 4.30's w/ front & rear ARB lcokers in my V6 5 spd XtraCab-
If you have the $$$/and or patience, you can find them-
I think I have managed to score 3 sets of front & rear 4.30's in the past 3 years.
I would offer this suggestion-
Post in the wanted section or possibly offer to "buy" lower gears for someone that has 4.30's
There will be guys with 4.30's that want to regear to 4.56, 4.88 or 5.29.
The problem is when the cost begins to equal or exceed the price of new 4.56's.
Price out what it will cost you in parts & labor for new 4.56's - use that as the ceiling for sourcing 4.30's