95 3.4l v6 103k 5spd

Well I was driving and there was a rock in the middle of the road (construction zone) I figured I could clear it, but I forgot about the flap underneath. Well It bounced up and hit my tranny. There is no damage that I can see but when I am in reverse and accelerate I hear a kind of grinding, it sounds like it is coming from around where the shifter is. Weird thing is when I jacked up my car on the drivers side, once I got it at a certain point it would make that grinding noise. If I jacked it up a little higher or lower it would stop. All other gears run normal.

So my question is what do you think I damaged? could I have just knocked the tranny a little loose or something?
The fact it makes the noise when I jack it up is a little strange and has me confused.