After reading the post that I linked above, I remembered that it was for a slightly different situation and is rather to complicated for this......
Basically, you must run a top shifting style transfercase as the 2nd case, and it would be nice to run a forward shifting style transfercase as your Crawl Box, since that is what your transmission and cab are designed for.
Also, in this case, like Ryan mentioned, you must put the 4.70:1 gear set in the last transfercase.
So you will need to convert your 4.70:1 case to a top shifting style transfercase in order for it to be installed behind the dualcase adapter.
And as for the front case, the Crawl Box, I would recommend (since you have access to many different transfercases) that you use the same style transfercase that you truck came with, a 1984-1988 Forward shifting transfercase. Then when you tear it down to build the Crawl Box, you will have the correct shift forks and rails for the design of your G-transmission and the shifter hole placement of your cab.
Becareful with forward shifting transfercases as Toyota produced two versions, the 1984-1988 and the 1989-1995. The first version featured shift rails that were slightly longer than the 2nd version. In my experience, it is more common to find a used first version than a used second version. So if your friend has 3 or more forward shifting transfercases, then I would compare the lengths of the shift rails that protrude out the front of the reduction housing (the front of the t/case) with forward shift rails on other transfercases. You should find a t/case that has a longer forward shift rail. If all of the rails are the same length out the front of the transfercases that you have, then I would put money on it that they are the first version.
Also, you could compare this to your 4.70:1 shift rails when you pull the 4.70:1 case out and before you tear it down to convert it to a top shift style.
Have fun!
Regards,
BigMike
