Do a search for KSC GLOCK 17 on DEN, it is on the 5th page 4th item down.
This link should work to the page its on.
http://www.dentrinityshop.com/den_se...17&pg=5&rpp=10
They label it part #87 and on the diagram its #83, but it is the correct part, Ive ordered them from DEN before.
Hope it works out for you.