Where is the piston 1 on Ford Freestar?

The Ford Freestar has a front-wheel-drive (FWD) layout. Therefore, it doesn't have a piston #1 in the traditional sense of a piston in an engine's cylinder. There is no piston numbered in this fashion within the engine's block itself. The numbering of pistons is done relative to the crankshaft and the firing order of the engine.

To find information about the piston location in relation to the engine's orientation, you'd need a detailed engine diagram specific to the year and engine type of your Freestar (they used several engine options). Even then, it would refer to the piston's position within the engine block, not a singular "piston 1" location externally visible.