You can use the 2.8 pump. Yes you can use the 3800 thermostat housing if you wish. Some put a refill cap on the hose. It is said that you can fill from the front and just take out the vent plug from the 3800 housing. I don't know if you can do that with the car flat but for sure you can if you raise the front.
[This message has been edited by phonedawgz (edited 12-07-2013).]