Correct..SS work was done by SLP, but I think that towards the end they were building the SS's at St.T using SLP sourced parts just as you would a regular Tier 1 supplier.
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2/20/2013: They Day the ****s Stopped
Only the SS hood and any slp options ordered where added at SLP's plant (CME,shocks, dif, etc)
All SS start as Z/28's shipped with dummy hoods to SLP, like JL8Jeff mentioned the dummy hood is noted on the build sheet