For 1996-2007, it appears Ford settled on:
- 58r as standard equipment for the Vulcan and Flex Fuel engines
- 36r as standard for DOHC/Duratec and an upgrade option for Vulcan & Flex Fuel
- 36r as standard for all engines starting around 2004
Keep in mind this tips:
1. Should be listed under "specifications" in your owner's manual.
2. Your parts store can look it up, sizes are standardized. Capacity
within that size can vary widely. Generally the longer the warranty the
better the battery (higher capacity) and the greater the cost.
3. Any Ford dealer should be able to tell you with a phone call too.
4. There should be a label on your present battery with the size and
Hope this helps (remember to rate and comment this).