New update: Tried to install the Cardone HD axle on the passenger (right side). the diff side was really hard to press in. But the hub side was the real issue! Couldn't get the hub flange to slide on to the axle. SInce I had the OEM axle on hand - I pulled out the CARDONE axle out and installed the OEM. It clicked into the front diff rather easily and the hub flange smoothly slided on the axle shaft!
Also, replaced the seal at the diff (where axle goes in) with a "National" brand one from O'Reilly. Buttoned everything up and noticed that diff oil is leaking from the new seal

Looks like I will need to pull the axle yet again and install an OEM seal - what a waste of a day!
The dingle berry on top of this fecal sundae is that installing a $400 OEM axle didn't fix the vibration at all