knock outs

i called my local dealership about a four wheel alignment and they gave me two different prices one for an alignment and a price if my truck (1999 slverado) had knockouts. what is he talking about?
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Knockouts on GM 4 wheel drive turcks with IFS.
You have what I'm calling two cam bolts where the upper A-arm mounts to the frame, Two bolts on each side at the upper mount. These cam bolts run throught the frame pockets (A-arm mounts) and through the A-arm. They physically control the postion of the A-arm. So anyway the holes in the two frame pockets are slotted (not sure of the right word to use here but anyway) These frame pockets where the upper A-arm mounts to the truck have partially slotted holes. These holes are where the cam bolts are adjusted for alingment purposes. From the factory they are only partially slotted on one end. The knockouts are where you take a special "j-tool" or other method to further open up the slots in these holes to allow for additional adjustment on the alignment.
Bascially the Knockouts are where one removes some metal around the cam bolt mounts holes in the A-Arm frame pockets to allow for increased adjustment on front end alignments. If they do this they have to remove the upper A-arm to get access to the mounting holes in question.
I believe they also want to sell you a "alingment kit" which to my understanding are new cam bolts for the left and right upper A-arms along with the matching washers and nuts.
I may have not used the correct termonology but its close. Hopefully you get my intent.
I'm not sure if they have to knock out the "holes on both frame pockets front and back or just partially. The holes look somewhat oval with extra materal on the sides that would allow one to remove these "special knockouts" to gain additional adjustment for alignment.
You really can't see these "holes" until you remove the cam bolts and then then the upper A-Arm.
I'm no front end person but I believe some trucks require the knockouts to be removed in order to get the vehicle alinged properly.
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