Automatic trans fluid lines question
Like Brian mentioned, the easiest way to determine which trans is by the pan. When you crawl under you'll see the trans pan surrounded by bolts. Compare yours to the pics above and below. Most of the time when you buy a pan gasket and filter they include both gaskets.
Look at the transmission pan?!?
The 727 will have a kick out as seen in the upper right corner of the picture, the 904 will have a corner cut off.
Like Brian mentioned, the easiest way to determine which trans is by the pan. When you crawl under you'll see the trans pan surrounded by bolts. Compare yours to the pics above and below. Most of the time when you buy a pan gasket and filter they include both gaskets.