2004 Limited

I just swapped my front diff with a complete 4.88 clamshell from ECGS to match the rear. Everything went smooth. I start testing 4wd by putting in 4hi and I get nothing. The light is solid, the front driveshaft spins but there's is no power to front wheels. When I give it gas the runner doesn't move nor does the rear driveshaft spins. Front driveshaft spins whether in N/D/R but no power to wheels.

I try 4l, same thing. I then put it back in 4hi and lock center diff and both 4h and 4l work. I don't think the front diff is actually engaged though, it's just the center diff locking driveshafts together that is pushing the truck.

Vacuum hoses are on and look good
ADD electrical connector is clean and looks good.
I can hear the front diff/ADD grumbling when switching to 4wd.

Any thought?

Thank You