that would definitely be your wheel cylinder.
or a hole in the line right close to the wheel cylinder...
take off the wheel, slide off the drum and check if the brake components are soaked. You'll have to replace the wheel cylinder and the pads and probably a few other parts too because the oil's all over them.
I had a blown wheel cylinder and I ended up putting new everything on (except the brake bar I reused), it's easier with new stuff and it doesn't cost that much really.
whenyou get your wheel cylinder make sure you get the proper inlet size.
1986 Ranger. 2.3L 5 speed manual.