Nope, you can't use any of those assemblies. This is part of the confusion I had.
The ONLY locker you can use is the one from the rear of an FJ80. No high pinion anything. No 8"ers from the trucks. Only the 9.5" landcruiser, non-high pinion third will work, and this is only from the FJ80 rear.
amaurer,
I guess I now know how my 7th grade algerbra teacher felt when she looked at my homework, " you got the right answer, I'm just not sure how you got there..."
The answer is that the only e-locking differential that will swap into either the front or rear axel housing of a 40 is the rear one from an FJ 80. The question is how we get there and why I'm still confused that the Marlin Crawler setups won't work. Here is how I got to my probably erroneous thought that the Marlin Crawler stuff would work. Acording to a lot of stuff that I have read including photos from this link from 4x4wire:
Erik's Toyota Differential info
My 1980 cruiser has a 4 cylinder 8" diff.
"
The
4cyl 8" diff
'79-85 Trucks and 4Runners all have 4-cylinder engines and use what most call the
4cyl 8" diff in the front (the same one they use in the rear)- see "
4cyl 8" diff" below. All pre-'95
4-cylinder 4wd mini-trucks & 4Runners use the Toyota 8" 2-pinion differential front and rear (
except turbo models). This is known as the "
4cyl diff." This diff is by far the most common diff in older Toyotas.- Ten 10mm ring gear bolts
- 27 spline pinion
- 2-pinion carrier (case)
- V6 carriers can be used in this diff
if the correct bearings are used
* LPH/SPH gear info:
Pirate4x4.Com Bulletin Board - View Single Post - ATTN: All, you must read! Toy FAQ
**
4cyl diffs are swappable with the V6 and high pinion diffs."
Using the identification photos and criterion my diffs match those pictured to a T. Obviously I have not opened it up to check the internals for identification.
4cyl has 3 ribs on each side. V6/Turbo has 4 ribs on each side and the trapezoid shaped top rib. T100/Tundra/Tacoma diff has the characteristic bearing truss.
Note- Starting in about '96, the V6 diffs started using a casting that looks nearly the same as the T100/Tundra casting from the outside. However, it doesn't have the trussed bearing cap on the inside, and the outside uses the smaller 8mm mounting studs."
Ok so that is how I got to the "I have an 8" 4cyl diff conclusion. Next the v6 diffs are swappable with the 8" 4 cyl diffs.
The
V6/Turbo 8" diff
'86-95 4cyl
Turbo and
V6* trucks and 4runners, and ALL
'96+ 4Runners use the Toyota 8" 4-pinion differential in the rear. This diff is known as the "
V6/Turbo diff." - Stronger housing than the 4cyl diff
- Larger carrier bearings than the 4cyl diff
- 30 spline axles
- 27 spline pinion (pre-'96)
- Ten 10mm ring gear bolts
- 8mm axle housing studs with 12mm nuts
- 4-pinion carrier (case)
- 4cyl 8" diff carriers (cases) do not fit without custom carrier bearing adapters ($), try
Inchworm Gear
- A few pre-'96 V6 trucks and 4runners have been found to have come with the 4cyl style diff from the factory. Nobody knows why.
* LPH/SPH gear info:
Pirate4x4.Com Bulletin Board - View Single Post - ATTN: All, you must read! Toy FAQ
'96-up 4runner V6 diffs:
- new improved housing that looks the same as the
T100/Tundra/Tacoma diff on the outside, internals are all the same as the regular V6 diff
- 30 spline pinion on OEM gears, swap pinion flange to 27 spline to use aftermarket gears
* V6 diffs are swappable with 4cyl and high pinion diffs"
I think that the Marlin Crawler setups are the using e lockers on the V6 turbo diffs which, according to this writer and his sources, swap into the 8" 4cyl diff:
"
Electric Locker
A factory option on 3rd Gen. 4Runners, Tacoma 4x4's, and Tacoma PreRunner 4x2's is an electric locking rear differential. This diff is a 4-pinon design based on the
Turbo/V6 8" diff and uses the same gear sets and bearings (except for the large bearing near the locking mechanism).
These locking diffs can be retrofitted into 8" diff axles if the axle housing is modified (
see this article for more info). It cannot be easily retrofitted into a T100/Tundra or open-diff Tacoma style axle housing because the mounting bolt pattern is smaller. It "could" be done by an axle builder by doing major work to the mounting flange, but that is not really a practical option.
- 30 spline pinion on OEM gears, swap pinion flange to 27 spline to use aftermarket gears."
looking at the axle housing shots here:
Differentials: Totyota Land Cruiser - Droput out with 9.5 ring gear. Found in both front and rear of Toyota Landcruisers.
the 8" 4 cyl and the 9.5 " seem to have the same external characteristics or maybe it's just late
. I guess at the end is there a definitive external characteristic difference between the two housings that I can spot as I go through salvage yards in third world countries looking for two of these? Again sorry for the long post just trying to get this straight in my head so I can translate it into Spanish and explain what I'm looking for to a guy who has even less of an idea of what this is all about.
John
The guys in the shop followed Drew's instructions step by step and they had it all in in less than two hours. I bought the diff lock switch and controller from Drew and again using his wiring instructions I put the wire harness together in just over an hour. 
Again I used an in cab diff lock switch and controller from Drew. For the front locker I got lucky as Sheldon included the wire harness for it with the shipment. What I did was clean that harness up, i.e. got rid of stuff that Toyota had spliced into it, as I already have those accessories otherwise wired and changed out the connectors as one was broken. 
