So i am a proud new owner of a super clean 01 xj! it is my first jeep, and i plan to keep it for a very long time.
when inspecting it, i noticed that parts of the undercarriage seem to have a rhinoline like surface on it. i didnt know if this was factory, or if someone put it on there before me. I'm pretty happy, because that was on my to do list haha oddly enough, they didn't do the actual frame...

But xjs don't have frames.. lol

well like the unibody frame. you get what i mean. the structural support that looks like a frame but really isnt because the mystical jeep cherokee is of the elusive unibody subspecies

Priceless.

Mine has this too... Being that it's behind the gas tank too, I'm assuming it's from the factory.

Jeep's term for it was uni-frame. And yes, they all look "textured".

Welcome to CF!!

Unit-Body and Unit-Bearings.
The short term is unibody, short for unit.

"In 1960, most Chrysler Corporation cars moved from body-on-frame construction to a unit-body design; the rest, other than Imperial (1967), moved in 1961."

Uniframe and unit bearings.