ariman,
I am not sure if it has the Electronic Locking differential or not. As far as I know, only the Parado uses an E-locker over seas.
If it has an E-Locker, then it should have an 8.0" differential with 2 side gears.
If it does not have an E-Locker, then it should have an 8.4" differential with 4 side gears.
I can't gather too much information from the VIN plate other than the R151F transmission.
For the common American, it would be easy to assume that this R151F is the same as the USA 1986-87 Turbo 5-speed transmission, but I believe that Aisin updates model numbers that have not been used for 10 years. So I would assume that your R151F is the same as our R150F, with a 3.83:1 first gear and a left-hand front output VF1A chain drive transfer case.
If this is the case, then if you use our adapter part number 34-4GT, you will then be able to place a RF1A gear drive transfer case behind your R151F transmission, and then use our MC09 adapter to return back to your stock VF1A chain drive transfer case. Your truck will then have a dual transfer case system, and the gearing options in the Crawl Box would be a 4.00:1, 4.70:1 TS, or a 4.97:1, however I STRONGLY recommend using our 4.70:1 Total-Spline gear set for reliability concerns.
Here is a picture of our Marlin Crawler Crawl Box that should fit in the application I described above.
Please note our EXCLUSIVE Total-Spline Input Gear:
If you could get me a picture of your transfer case, and even better, of the rear of your transmission with your transfer case removed, then we could be much more accurate with the required application.
Regards,
BigMike