Joe C

I picked up a couple upper/lower control arms from an 87 corvette at an on-line wrecking yard. i'm rebuilding these for a suspension rebuild project. one thing I've noticed is on the lower control arms, there are these markings. on the very bottom of the arms, the one is stamped with "4Z51" and the other with just a number "9." they both came off the same car (but I do realize they may not be OE original to the car). so my question, does the
Z51" thing indicate the suspension option, and the big question, are Z51 control arms different than non-Z51 arms? both arms appear to be identical except for the R/L thing and the markings. the ball joints seem to be a bit different, so they may NOT be off the same car. any difference in Z51 and non-Z51 ball joints? i'm not seeing anything on, on-line parts applications, indicating any difference. --



any insight to the markings???

notice the difference in the ball joints - again, can't say they are OE original to the donor 87 and no guarantee they came off the same car. the difference in the ball joints leads me to believe they are not a matched set of control arms, but the dates codes indicate they may - ??? - somewhat confusing....

WVZR-1

Z51 control arms got different bushing during assembly. Was the '87 a Z51 car? Never seen comments regarding ball joints and I'd doubt that differed in production.

**I've never paid any attention to 'Julian date' codes on LCA but it's certainly possible that there might be. Inspect maybe more closely. The Z51 is mentioned often.

81c3

Maybe the one ball joint was replaced.

Joe C

good call on the bushings - . from strictly a PHYSICAL appearance, they look the same, but that does not mean much, only the appearance. ball joints - who know? the GM standard parts manual does not differentiate between base and Z51 control arm assemblies - there's only one part number. that's my confusion -

date codes: should have clarified this. I cannot find a date code on the LCA assemblies themselves. there some markings, but I do not recognize them as dates. when I received the assemblies the lower shock mount brackets were still attached. both appeared to be original to their LCA assemblies. one has a date code of 7987 (79th day or march 20th, 1987) the other 12087 (120th day or april 30th, 1987). it's not 100%, and I can't swear to anything, but it's close enough to be a matched set. one final thing, there were salvage yard tags on the parts - both ID'd the car with matching VIN (1G1YY2181H5125879) for what that's worth.

probably doesn't mean much for my needs. both will be broken down to the basic control arm - fitted with new bushings and ball joints.

edit: i'm somewhat convinced that these lower control arms came off different 1987 cars that somehow got mis-labeled.