2004 4WD Not engaging but no service light

[KYSock]

Howdy, my 4wd went out last winter on my 2004 1500 auto and I'm finally getting around to fix it. Some things I've figured out in my self diagnosis. The 4WD light does come on when shifted into either 4WD-H or 4WD-L, moving the front drive shaft by hand does move the gears in the front differential, the drive shaft moves when in drive/reverse. The passenger side CV Axel has a decent amount of play.
Also while I was doing research before I went under my truck to take a look I thought that all 3rd Gen 4x4 models had an electric actuator that's on the passenger side of the front differential, but once I got under the truck I found that to not be the case, and If I'm gonna be honest I still don't fully understand what makes the 4wd engage the front wheels is it a vacuum system or an actuator that I just can't find.
But I hope I can get some help to more understand the 4wd system in my truck so I can make the correct fix.

 

[Lyle Longboat]

There is a lever/rod that goes down from the floor shifter and back to the transfer case. I’d start looking there and see if anything is broke/loose/seized. 02/05 has this lever, I’m not totally sure if the 06-08 has the same rod/lever or if they switched to the front actuator.