I got the 1012SP. It came with the Street Performance shocks. I love them. A lot of guys on this forum think they are to stiff, but I don't think so. Had the nitro drop shocks on my 2002 and didn't like them. Love this kit on my truck it rides great. This kit works with steel control arms.
https://www.belltech.com/products/belltech/lowering/complete-lowering-kits/with-street-performance-shocks/belltech-2016-5-2018-silverado-sierra-std-cab-2wd-3-4f-5-6r-with-street-performance-shock-1012sp.html