I'm a little confused on how the Posi-Lok CAD replacement works. Does it lock and unlock the front axle or what?

 

it uses a manual cable to replace the vacuum operation of the shifting (coupling) fork.
the shifting fork couples the 2 piece passenger side axle shaft, which delivers power to the front tires, instead of them just coasting along.
standard factory operation is that a vacuum switch on the transfer case automatically sends vacuum to the cad, which automatically couples the front axles whenever you shift to 4hi or 4 low. a posilock gives/forces you to manually engage the axles, in addition to shifting the t-case.
think of it as seat operated locking hubs.

http://www.dodgeram.org/tech/repair/...CAD_engagement

 

So in theory i could have a kind of unlocked 4x4 if wanted with it? That's cool.

 

no.
posilock cable provides
1. a more positive/sure/foolproof coupling of the passenger side shaft, that is less likely to fail when you need it due to leaking, torn up vacuum lines. if you don't have this coupling, then your front tires are just freewheeling, and you don't have 4wd.
2. the ability to have 2wd low range, by shifting the transfer case to 4lo and then NOT locking the front axle. this gives you low range torque and slow trail speed, w/o the front wheel bindings in turns. good for rough, non-slippery dirt roads.

 

but that site makes it sound liek the drivers' side shaft will sitll have drive in 4x4 and the posi-lok just allows the passenger-side to lock up to it. So if it's unenguaged but in 4x4 the drivers' side will still be pulling.

 

no u will still be in 2wd. since the diff is "open" and the passenger side intemediate shaft spinning. all the power is going to that inner shaft insted of the side with the tire. if you had a locker in the front u would have (3) wheel drive

 

hhmm. i never thought about that. i wonder how it would drive in 3 wheel drive. i guess the drivers side would still bind up in turns, but otherwise it wouldn't be much different from regular 4wd which is actually 2wd as opposed to 2wd which is actually 1 wheel drive. i wonder if anyone can figure out how to couple the spare tire then we'd have 5wd. yee-haw.
posilock on order i hope it warms up so i can put it on.