Cool - Thanks for the info.

To get a little more accurate...  I believe my transfer case is the chain driven - need to double check this, but at the moment I'm in Canada, and my truck is in Texas - won't be able to crawl under it for another 6 or so weeks.  In any case, I'm pretty sure it's chain driven, and is the r150f transmission.  Also, the engine was originally from Japan - RHD vehicle.  It's now in a LHD 4runner.  Do I need a right hand or left hand output?  I believe right hand, but could be wrong.  Assuming I need a right hand output, and have a r150f transmission and chain driven transfer case, am I correct in thinking my options are as follows:

A complete dual transfer case setup, swapped in, tearing my old transfer case out.  ie. this kit:
http://www.marlincrawler.com/transfer-case/line-ups/dual-t/cases/gear-drive-right-hand-front-output-dual-transfer-case
This would completely get rid of the stock chain driven transfer case, correct?

Or, I can add in the crawl box only, behind my existing chain driven transfer case, using this option:
http://www.marlincrawler.com/transfer-case/line-ups/crawl-boxes/gear-drive-unit-right-hand-output-chain-drive-tcase

Are there any differences between these two options?

And, will these bolt up, and if not, which adapters are required?  I've been reading through the website, but I'm not exactly sure which is for which application yet.  Thanks,

Spruce