I recently purchased a 97 ram and when I went to engage the 4x4 with the Posi lock that was previously installed on the truck, it didn’t engage and then caught later one when trying to drive it through some mud. I took off the cover to where the CAB was located and noticed that the shaft to the left was able to be pushed about a 1/2 inch. My question is is this normal or is there something broken on the front diff

This was it when I first opened it

And this is what happened when I pushed the locking mechanism over trying to see if it would Slide Over on it
erential

 

Take the cover off the diff and have a look, Probably an issue with the spider gears.