Ok so now that we have gone over "Top Shift/Forward Shift" the next big difference between cases was the input shaft size. Toyota made 2 flavors of these, 21 Spline and the bigger stronger 23 Spline...
23 Spline on the left, and 21 Spline on the right...
Now which one do I have you may ask yourself? Here is a list of Toyota Transmissions and T-Cases according to shift style and spline count. This will give you a better idea as to what you may have. (list taken from Pirate)
Year Model Application Model Speeds Splines 1st Gear Engine Transfer Case:
1979-1980 Carb L43 4sp 21 spline 3.67 4cyl 20R Gear driven Top Shift
1981-1983 Carb L45 4sp 21 spline 3.93 4cyl 22R Gear driven Top Shift
1981-1983 Carb L50 & L52 5sp 21 spline 3.93 4cyl 22R Gear driven Top Shift
1984-1986 Carb G52 5sp 21 spline 3.93 4cyl 22R Gear driven Forward Shift
1986-1988 Carb G54 5sp 21 spline 3.93 4cyl 22R Gear driven Forward Shift
1986-1987 EFITurbo R151F 5sp 23 spline 4.31 4cyl 22RTE Gear driven Forward Shift
1985-1988 EFI W56 5sp 21 spline 3.95 4cyl 22R Gear driven Top Shift
1988-1991 EFI R150F 5sp 23 spline 3.83 V6 3.0L Chain driven Forward Shift
1989-1995 EFI W56 5sp 21 spline 3.95 4cyl 22R Gear driven Forward Shift
1989-1995 EFI/ADD G58 5sp 26 spline 3.93 4cyl 22R Chain driven Forward Shift
1996-2002 EFI W59 5sp 23 spline 3.95 4cyl 2.7L Chain driven Top Shift
1996-2002 EFI R150F 5sp 23 spline 3.83 V6 3.4L Chain driven Forward Shift
SO pretty much it's the R151F (Turbo Tranny), R150F (V6 Tranny) and the new Chain drive T-Cases that come with the bigger imput shaft...ideally a full 23 Spline Case and crawler box should be what you shoot for! But if that is not in your budget it's not a big deal. Most of us have the 21 Spline cases, and there is nothing wrong with the 21 spline case at all.
Now a lot of people always debated about should I just go with a single 4.7 gear set or should I go with a doubler setup. Well after Wheeling with both styles I've been sold on doubleing up, having the option of the stock 2.28 low range gear is really nice. There are a lot of times when the 4.7 is just to low to cruise around and 4Hi is well just to high. Yes there will be a bit more of $$ involved because of having to re-do your driveshafts, but in the end you will be happier. If you have never wheeled in double low its totally different, but in a good way of course! Everything slows down and it allows you to have more control.
