Coolant Leak (Drivers Side) ? 1999/2.4
 

Ok so I have had a small leak for about 1 month, coolant would go low and couldnt find where it was coming from. Last night it started leaking bad, good thing is I know from where. The housing on the drivers side of the engine, right underneath it.

Now for someone who has fixed this already:

Is there a gasket that needs to be replaced or the whole unit ?

Any tips when taking it off to repair (doesnt look hard at all, but never know) ?