As long as the joining of the two cases is done correctly, you keep gear oil in the cases, and keep the rear drive shaft in good order, dual cases are as durable as the oem one.
Use:
2wd high
Front case in high, rear case in 2wd.
2wd low stock gears
Engaging front case w/stock gears, leaving rear case in 2wd high.
2wd low 4.70 gears in 2wd low
Engage rear case in low,(as you can now with just the stock case), or if you add twin sticks, shift the rear case into low, leaving the 4wd side in 2wd location, and the front case in high.
4wd single:
4wd High-engage rear case into 4wd, same as you do now w/stock case, leaving the front case in high.
4wd Low stock gears:
Engage rear case into 4wd Hi and front case into low.
4wd Low 4.70 gears:
Engage rear case into low, leaving front case in High
4wd Double low, engage both front case and rear case into low.
Once you get out and have a chance to play with them, you will find out what combo works best for you.
If the twin sticks wont allow for you to retain your arm rest, you can still keep it w/a little fab work.
Wanting to have usable space between my shifters for switches, I extended the front case shifter so that it would sit next to the rear case shifter.
Extension
Installed
You could do something similar in reverse with the rear case shifter sitting up with the front case along w/a short throw shifter kit to reduce the movement that the shifter needs to engage the rear case. I have a 2" body lift on my '91, so I had room to run the extension under the the cab, leaving the trans hump intact, you might have to cut out the sheet metal between the two shifters, or run the extension across the sheet metal.
There is also a triple stick option(when both cases are top shift cases) that doesn't cost that much more than twin sticks,
http://www.pirate4x4.com/forum/showthread.php?t=976944Same product now w/own website
http://radesignsproducts.com/TripleSticks.aspx
