How necessary do you think they are? Are they mostly just to keep mud off of stuff? There's a flexible strip that connects to both left and right side covers that seems to just cover the engine support crossmember, although there is a harness there too. Maybe its to protect the harness, although its so flimsy any protection is dubious.

Some clown removed all of the undercovers on my newish-to-me 97 and I'm in the process of removing them from my 93 parts van to transfer them over. Looks like all of them will transfer right over except the front one, which I'll have to modify to make room for the intake tube