whoaaaaa my mind is totally blown! I figured once I swapped the vacuum lines and got the 4WD light on the shifter became useless but I had it totally wrong!

 

Nope! The cad just connects the axles. The transfer case actually transfers the power (hence the name). HeyYou explained it really well.

 

I learn something new. Every. Single. Time. I come here

 

That's good

 

Ok so another question. I always thought that when the front driveshaft doesn’t turn that means the 4x4 is engaged. (I realize this may be true “traditionally”) but in my application what is a definitive test to make sure 4WD is truly engaged or disengaged?

 

Get the back wheel stuck

 

lol that’s one way I suppose

 

Unless you feel safe putting the whole truck on jack stands. Usually what I do is find a gravel parking lot and engage 4wd if it "jumps" it's in 4wd

 

theres 4 inches of snow on the ground right now. I think I’ll block the back wheels and see if the front ones dig in/spin that should work no?

 

It should. I would try to get the truck "stuck" like for example my driveway has a little hill and if you stop on it with snow you need 4wd. That's how I test it.