The G- and W-series front transmission housings both have the same bolt pattern, so their bellhousings are interchangeable.
With that said, the stock Tacoma W59 bellhousing is used on any type of G- or W-series transmission, which all have the same input shaft spline count (21), length, and pilot. So the W59 Tacoma bellhousing allows for a G52, G54, and W56 to be bolted directly behind a 'RZ' engine block.
Now as for your G-series transmission, which is a G52, or the *weakest* aluminum 4WD 5-speed transmission ever used by Toyota, I HIGHLY recommend AGAINST using it or any other G-series transmission behind *especially* the 3RZ. Remember that the 3RZ has nearly the same torque output as a 3.0l V6, and putting a G52 transmission behind a 3.0 in a heavy 1995 4Runner is not something Toyota would have done.
In fact, when we did Bevin's 3RZ Swap, we swapped a 2003 3RZ into his Carburated (G54) 1985 Shortbed, and right now that transmission is on its LAST LEG. After our run up at Bald Mtn this past weekend, Bevin told me that if he doesn't get a better transmission by Christmas, he doesn't think his G54 will last into 2007. His Transmission is making so much noise that you can't even drive it above 80 MPH. The whole truck shakes and it feels like something is going to blow up. If you put it in 4th gear it sounds better, but I am sure that both his main bearings and especially the counter and 5th gear bearings have about had it.
~180 ft-lbs torque is NOT what the G-series transmission was designed for. Remember that the original Hilux G-series transmission used (the G52) was offered with an engine that only had a maximum torque output of just 129 ft-lbs.
The W56 is a lot better than the G52 and a bit better than the G54. Toyota did use the W-series transmission behind the 5M-GE power plants of the 1981+ Celica Supra, but remember that the early US-version of the fuel injected 2.8l 5M, the engine used with the first 5-speed in the W-series, the W50, developed but just 145 ft-lbs torque, or about 35 ft-lbs LESS than the 3RZ. This 5M is much more comparable to the fuel injected 22R-E, which was also fitted with a W-series transmission (the W56 of course), rated about 140 ft-lbs torque.
So when you look at how Toyota introduced the transmissions, then you can understand what they had in mind:
|Transmission Introduced ||Engine Used ||Year ||Torque Rating|
|L-series (L43)||20R||1979||122 ft-lbs|
|L-series (L45)||22R||1981||122 ft-lbs|
|L-series (L50)||22R||1981||129 ft-lbs|
|L-series (L52)||22R||1983||129 ft-lbs|
|G-series (G52)||22R||1984||129 ft-lbs|
|G-series (G54)||22R||1985||129 ft-lbs|
|W-series (W56)||22R-E||1985||137 ft-lbs|
|R-series (R151F)||22R-TE||1986||173 ft-lbs|
Also, other Toyota models include, but not limited to:
|Transmission Introduced ||Engine Used ||Year ||Torque Rating ||Notes|
|G50||2KD-FTV (diesel)||199?||147 ft-lbs||Very high TQ rating for the G|
|First W-series (W50)||5M-GE||1981||145 ft-lbs||2WD Celica Supra, Curb Weight ~3000lbs|
|First R-series (R150)||3VZ-E||1988||180 ft-lbs||2WD V6 Hilux. R150 is the first in the series,|
but the R151 was introduced
two years prior in the
2WD 22R-TE models
Now some like to say that Toyota "Over Engineers there vehicles", and I believe this as well, but when you compare what the transmissions were originally intended for with the torque ratings of future engines used, it is quite evident that Toyota in fact did Over Engineer their transmission, and this is evident in the W-series:
W-Series fact of "Over Engineered"
|Engine||Model||Year||Torque Rating||Vehicle Weight|
|Originally used behind a||5M-GE, 2.8l I6||W50, Celica Supra||1981||145 ft-lbs||~3000 lbs|
|Retired with use behind a||3RZ-FE, 2.7l I4||W59, Tacoma||2004||177 ft-lbs||~3400 lbs (Crew Cab)|
So Toyota used the same series transmission in a vehicle (the Tacoma) that weighs apprx. 400 pounds more behind an engine that develops apprx. 35 more ft-lbs of torque than compared to the Celica Supra, which was the original vehicle used with the W-series transmission.
Now if we hold this same truth of the W-series transmission to the G-series transmission, then the "Degree of Over Engineering" required for the G-series transmission would only allow an engine of about 165 ft-lbs of torque (add 35 ft-lbs to the 1984 G52 setup). And this is only true if the G-transmission is as well built as the W-transmission, which we know it is not.
So even if we consider Toyota over engineering the G-series transmission, I would say that they would only suggest its use with engines up to 160 ft-lbs of torque. The 3RZ-FE is therefore nearly 20 ft-lbs of torque too much for the G-series transmission to be used in a "reliable" nature, if one follows my bizzar method described here.
Perhaps even more evident, but not related to our discussion, is the degree of Over Engineering of the 5-speed R-series. In this case, a 400 lb heavier vehicle is fitted with an engine that produces nearly 50 ft-lbs torque more than in the original case:
|Engine||Model||Year||Torque Rating||Vehicle Weight|
|Originally used behind a||22R-TE, 2.4l I4||R151F, Hilux||1986||173 ft-lbs||~3000 lbs|
|Retired with use behind a||5VZ-FE, 3.4l V6||R150F, Tacoma||2004||220 ft-lbs||~3400 lbs|
|Optional Dealer Installation behind a||5VZ-FZE, TRD Supercharged 3.4l V6||R150F, Tacoma||1996-04||~300 ft-lbs||~3400 lbs|
So you can buy a R-series equipped Supercharged Tacoma with a factory warrenty that exceeds the original use of the R-transmission in a Toyota truck by a good 125 ft-lbs of torque. Now that is saying something about the R-series transmission. That says something that no L-, G-, or W-series transmission could even dream about!
Well, that is my own goofed up form of Toyota Transmission logic, and if you chose to follow it or not, I had fun researching it
I'm sure there must of other models that used some of the transmissions listed above that I did not mention, but for the sake of just Hiluxs and just Hilux transmissions, I think I covered it ok.