Heres a before and after

The aluminum housing comes with a pressed in fitting with loctite. I uses a propane torch to heat it up and vice grips to pull it out.

Then..

I had the guys at Amazon Hose in Tampa tap out the hole to 1/2 NPT for a few bucks and I installed the 1/2 NPT hex plug. Pretty snazzy and cheap.

Total cost less than 20.00

edit.. look how the rubber cap starts cracking.. imagine if that thing lets go and coolant hits the track when you hauling... big time bad newzzz. Now you know why I made the change.. I also installed a 160 stat and drilled a couple 1/8 inch holes into it.