Something next to alternator leaking, need ID on what it is

Hey guys, 1990 Legacy wagon has recently been making a burning electrical smell that I've noticed at stops with the windows down. On further inspection, there's a little thing, I don't know if I would call it a sensor or valve, but it has an electrical connector and looking at the engine from the front, it's on top of the engine in the crevice to the left of the alternator:

 

http://abload.de/thumb/2013-05-28_15-36-32_78iu4a.jpg

 

I looked at the same part on a 2008 Forester we have and it's nice and clean so it's definitely not supposed to leak like it is. Can anyone tell me what this part is called?

 

edit: I found a picture that has a little better view of it:

 

http://farm8.staticflickr.com/7008/6522719695_9c83e91249_o.jpg

 

it's the thing to the right of the power steering fluid reservoir, right below the EJ22 stamp.

that would be the oil pressure sending unit. their under full oil pressure, so they have a tendency to leak. Their not expensive either,.

that would be the oil pressure sending unit. their under full oil pressure, so they have a tendency to leak. Their not expensive either,.

 

True statement. Easy fix.

Thanks guys. Is this something that would be ok to buy aftermarket or should I get it from Subaru?

I bought one from advance, hasn't caused me any problems yet.

yeah, these are pretty simple things, I wouldn't worry about using an aftermarket part.