Lately, I've been hearing a grinding sound as I make a right hand turn, even at slow speeds. I've never been able to find the source of the sound, although when I stick my head out the window it sounds like it's coming from the rear. Today it was starting to feel like it was harder to get in gear, the motor got a little warm (starting hearing some pinging when accelerating under load), and I burned like twice as much gas as I should have on the trip I took. At highway speeds, when I would let off the gas to decelerate, I could hear a low pitch hum/rumble/grind. When I got it home about 50 miles later, it was leaking what looked like motor oil. I couldn't quite pinpoint the location of the leak, as there was oil splattered everywhere, but it seems to be heaviest where the engine and transmission meet. When I checked the oil level, it was the same as two days ago when I checked it. Also the oil is very clear on the dipstick and the stuff in the driveway is very black and feels gummy. I have also been hearing a rattle in the shifter that wasn't there before. I was thinking it was probably due to shifter bushings, however now I am wondering if it is possibly another sign of a dying transmission. I am thinking that my transmission took a dump on me, but it is still driveable. In my way of thinking, a transmission problem could account for the excess fuel usage and the engine cooling problem if the transmission was binding. My questions are: Does this sound like a transmission problem to you? If so, is it something that can be fixed by the somewhat capable home mechanic, or does it need to be replaced? I'm certain I can do the replacement myself, however I have never seen the inside workings of a manual transmission.
By the way, this vehicle is a 1974 Super