If you register with Autozone there is a repair guide for your truck. Here is a link to the section on starter replacement.
https://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f803715a1
I had a 2000 Blazer 4wd awhile back, I let my mechanic replace the starter. In theory the starter should come right out on a 2wd. The 4wd starter replacement is a bit more involved.
Good luck,
Ed B,