i often use this saying:"just because it can be done does'nt mean you have to". it applies to our hobby in soooo many ways. i know this isn't going to win me any popularity contests around here but i don't think that 4 door wagons make for great rock rigs. they're just too heavy, there's too much overhang and not enough visibility. so unless you're willing to heavily modify, invest a lot of time, money and effort, there might be better ways to go about rock-crawling.
wagons do make great camping and expedition rigs however.
sure, you can retrofit different powertrain components intop a wagon to get the power to weight ratio up but then you're still dealing with lugging 6000 pounds or more thru the trail. i bet most wagons will tip the scale at 7k or more once fully loaded for a wheeling weekend. that in turn puts more stress on stock components like drive shafts, axle shafts, pinions, birfs,.......and the viscious cycle begins.
cutting the roof off and loosing all the glass but the windshield definetly helps in the weight department and brings down the center of gravity. most canopy/boat shops can make custom tops for vehicles. but they're not going to be cheap.
ask me, if you want something with decent interrior room yet nible enough for the rocks, then build a 4runner. if you want to wheel a cruiser in the rocks, then a 40 would be a smart choice.
"flame suit on"
georg