I thought about it being to low at first too but I crunched a few numbers and this is what I got...
Top gear rpm for 60mph
th700r4 and 5.99's 2285rpm = 60mph on 37's
sm420 and 5.99's 3300rpm = 60mph on 37's
TH700r4
1st gear 3200rpm = 19mph on 37's
2nd gear 3200rpm = 36mph on 37's
3rd gear 3200rpm = 59mph on 37's
4th gear 3200rpm = 84mph on 37's
Crawl ratio with Toy T-case
th700r4 and 5.99's stock single case = 41:1
th700r4 and 5.99's with d/case, stock gears = 95:1
th700r4 and 5.99's d/case w/2.28+4.7 gears = 196:1
th7004r and 5.99's d/case w/2x4.7 gears = 404:1
sm420 and 5.99's stock single case = 95:1
sm420 and 5.99's with d/case, stock gears = 218:1
sm420 and 5.99's with d/case, w/2.28+4.7 = 447:1
sm420 and 5.99's with d/case, w/2x4.7 = 912:1
I think with a th700r4 with it's OD of 0.7 and 37" tires 2285 is a good rpm for a 4.3 V6. And it's easy to get a good crawl with just a dual case setup, 4.7 gears wouldn't even be needed unless you where really hardcore.
Breakage is an issue but a small one I think they are after all ex military gear. Armys have it made tough and to take abuse, plus guys in Europe right now are racing these in formula off-road and they are holding up well. And being a portal axle the greatest torque forces will be below the shafts in the reduction, so less strain on the really expensive parts. Good for the reat of the drive line too.
Here are a few more pics I found of the inside of `em...
C303 3rd member
Volvo's idea of a birf'
Spur gear in the reduction unit
Disc brake conversions can be done on these axles with parts from Wilwood.
The dry weights on these are front ~180kg and rear ~155kg, so do these sound good to anyone else besides me?
BTW Lars...
I think that a 304 would be the best ****** camping rig a person could ask for! Add a pop top, that was the first thing I thought of when I saw them... I'll be buggin' Vince at real4x4 to import them too as well as the 303's he has planed. If you really want one rumor has it that you can get a complete 303 in europe for $2000 to $3000usd.