Lower ball joint part #s

[Roscopcoletrain]

So I know 19209396 is the stock #. Dealer wants $115.56 for oem. (cdn). Rock Auto has em for $85. But they also list the MOOG K500007 for $38. https://www.rockauto.com/en/moreinfo.php?pk=1448340&jsn=260 Is this the economy model or the better one? Called my local napa who has a lifetime model for $111. 

 

Edit..to make it more confusing, MOOG website lists K6541 as the proper part#. This is $49 from Rock Auto. 

https://www.fme-cat.com/overlays/part-detail.aspx?brandId=MC&pNum=K6541&partType=Ball Joint

 

I AM CONFUSED! 

 

 

[Roscopcoletrain]

SOOOO I think I have this figured out. The k500007 are for Alum A arms, k6541 are for steel. 

I assume this isnt the economy part though?