Missing lower engine cover?

Hi, yesterday I bought a nice 2004 5-lug SR5 2wd Xtra Cab. I previously owned a 1990 SR5 2wd. The 1990 had a trapezoid-shaped lower cover (plastic if I remember correctly) that helped protect suspension and lower engine components. It mounted somewhat between the front wheels underneath the engine. If I remember correctly I used to have to remove this cover to drain the oil.

My question: should there be a similar cover on my 2004 5-lug? There are some mounting holes on the bottom-front of the front fenders that look like something may supposed to be there. Keep in mind this is just a 2wd, non-prerunner, low-to-the-ground old guy's truck. I'm not talking about a true off-road skid plate, just the little protection cover. I've tried google image search, but just get pics of 4wd or prerunner skid plates, not much help. The truck is so nice I'd like to put it back to original if anything is missing.

Thanks. -Dan