Differerances in 4th gen upper control arms

Doing front end work this weekend, bushings, ball joints and tie rods. A friend of mine gave me upper control arms with good ball joints. Plan was to just put the energy suspension bushings in those, and just swap them out. However after looking at those and the ones on my car, I discovered that the ones on my 94 z28 are boxed in if you will. They have a metal strip welded in around the stamped UCA. Now the ones my friend gave me are just stamped with nothing welded in the "channel".

I bought the car new, so I was just wondering about the differences in years ect ect.

that's weird, I don't recall the UCA's on my 94 being boxed at all.

Not sure of the model or year the UCA's my friend gave me. He buys and parts out totalled 4th gen f-bodies and tries to get only LS1 cars or 6 speed lt1's. I don't think he has ever bought a 6 cylinder car at all. I took another look a little bit ago and my stock UCA's are "boxed in" with a one eighth'th or quarter inch think metal strip.

Like stated before I bought the car with 6 miles on the odometer so I know it is for sure factory. Oh well who knows?