I just had a used tranny put in my 05 neon and 2 days after i noticed it was leaking tranny fluid. I cant tell where its coming from and dont really know what to look for but i need to find out where its coming from and how tofix it

 

Put a piece of cardboard under the car.

 

I'm guessing you have an auto Trans. I would check the bottom drain pan seal. Also, there are 2 cooler lines that go from the trans. to a cooler by the radiator. My cooler line was leaking at the trans and I thought it was leaking from the pan since I just replaced the fluid and filter. If it's dirty under the car give it a shot of engine cleaner to help see where it might be leaking from.