When I'm cruising between 40 and 45 in 3rd gear I get a clunking or slipping in the trans. It only happens at these speeds and if I give it a little more gas to accelerate, or let off all together it stops. Shifts are fine also.
I just changed the fluid and filter because it was doing this but that didn't make much differance. I'm thinking about doing it again and adding some Lucas transmission conditoner, does anyone have experiance with this stuff? I'm not talkion about the super thick slip fix, I'll get it rebuild before I add that stuff... But is the conditoner any good?

I'm welcome to any other soloutions also