Why is my xr3i leaking oil?? ?

Ok so i aqquired a xr3i cab, mk4...i think...its an Hreg, 91!!! so i went under it today as i saw some leakage on the floor, there seems to be some sort of bolt, silver, bout 2 and a half inches hanging down from a hole, not sure if its the sump, you can push it up and down, its located in the centre of the car behind the engine, like on the same leval as the start of the window screen, its dripping away, i moved the car back and left it for 30 seconds, then did the same again and its leaving some patches on the floor, seems pretty fresh tho, not that black, i only got the car 2 days ago as a bit project, what the hell is it?? is it the sump?? if so whats the bolt/screw doing hanging down aragh!!!!!