TH400 Transmission using Fluid...but where is it going???

[southplainsag02]

I just recently purchased a 72C10. I believe it has the TH400 Transmission. When I pulled away from the place of purchase I added a quart of transmission fluid. I drove it at most 10 miles and it has been parked for 2 weeks while I tinker with it. Tonight I had to put in another quart to get the fluid to the correct level. There are no visual signs of leaks on my garage floor. Is this leaking around the transmission and then collecting dirt or what?