The Sport, Sport Trac and the 4-door Explorers all use the same basic front suspension parts, all three models were available with the SOHC V6 (which would have had the same weaker 5R55 transmission) but the 4-door could be had with the 5.0L V8 in 2WD or AWD using the more reliable 4R70W trans.
There are many things that are unique to the Sport Trac, so it's best not to think that everything is interchangeable between the 2-door and ST. It strikes me odd that everything up to the ST's rear doors isn't the same between the Sport and ST, but I learned the hard way they are not. If you order parts from RockAuto you'll notice that they ask if you're buying parts for an Explorer, Sport or Sport Trac.
I don't know when the OHV V6 was discontinued, 2000 maybe? The SOHC V6 has had and continued to have had problems with the timing chain components breaking. Unfortunately when this happens it eventually leads to catastrophic engine failure. Even if repairs are made early the cost of making the repairs is very labor intensive are requires engine removal to access the passenger side chain components (repair costs typically exceed $2000). You'll know when your TC's are failing when you hear the infamous "4.0L SOHC timing chain death rattle" (your engine starts sounding like you have a diesel). It's not a matter of if this will happen to your engine, but when. There are many threads on this subject. I suggest you do your research to know what to listen for.
