An amber color would probably be old(er)antifreeze, since transmission fluid is usually more red or reddish-brown in color, but if the fluid has been in use for awhile, it could kind of go either way. Do you have some extra antifreeze and transmission fluid around to compare the actual smell of the fluid? Antifreeze has something of a sweet smell, and transmission fluid smells more like...uhm...an armpit?Yeah, not the best smelling stuff ever made.