If the pump works and the housing is not damaged, you should not have to separate or replace either. The pump could be had at NAPA, just tell them what it is for. They likely will not have the housing, you will have to use yours.
If the pressure fitting is bad, you could get a new one from Chevrolet, I don't know if they are available from NAPA or other parts houses. There is an o-ring on the fitting. The fitting on the back can be replaced without pulling the pump off the engine. If you did not pull the housing and no one has damaged it by prying on it to tighten the belt, you should not have o-ring trouble.
The outlet fitting needs to be tight and sometimes tightening the pressure hose can work it loose. That could be your leak. The flared end of the hose or the threads sometimes can be damaged during the install and cause leaks. The hose end or the hose itself could be leaking.
There are several holes in the front of the pump that are used for different brackets so any pump should fit your bracket.
If you click on "Use Full Editor" at the bottom of the "Quick Reply" window, pictures are very easy. A couple of pictures would make this easier. Clean off the leaking oil with carb or brake cleaner and a air hose, then run the engine just long enough to get a drip or two to tell exactly where the leak is. I find its best to have someone else start the engine while I watch for the leak, sometimes it takes more than one cleaning to find it.
