I've been running dual cases with 2.28 in front and 4.7 in the rear behind an A340F for about 5 years now. I've been through the Rubicon many times as well as Clawhammer, Deer Valley and many others. Here's the article I wrote back then:
http://www.4x4wire.com/toyota/tech/autocrawler/I have found that I use the 4.7 gears most of the time when I'm in rocks. When it's light wheeling in dirt/mud I use the 2.28 gears. When I need to control braking down a steep descent, I use both gearsets. Here's a table showing my crawl ratios.
The spacing gets screwy when it posts, but you can figure it out if you look at it long enough
A340F w/gear driven dual cases
Xfer #1 Xfer #2 Total R/P 1st 2nd 3rd 4th
2.28 4.7 Reduction 4.88 2.8 1.53 1 0.71
H H 1 X 4.88 13.66 7.47 4.88 3.46
L H 2.28 X 4.88 31.15 17.02 11.13 7.9
H L 4.7 X 4.88 64.22 35.09 22.94 16.28
L L 10.72 X 4.88 146.42 80.01 52.29 37.13
Phil
