From 1986-2014 as of the date of this post - The site has gone cold. I had an account that stopped working last month. They won't answer calls for support ...

The site has gone cold. I had an account that stopped working last month.

They won't answer calls for support now.

Sent from my SM-N975U using Tapatalk

Same for me. It worked about a year ago when I was having starter problems, no-go now, too bad.

Yup, I really liked having access to the diagrams.

The GM wiring diagrams for 1967-1994 trucks were scanned and posted to a couple other forums that cater to those older trucks. Those years Silverado and Sierra were trim levels not models.

Mitchell has newer wiring diagrams but they aren't always 100% complete or absolutely correct.
If you intend to keep the truck for a while I'd look for copies of the GM service manuals.
They are pretty pricey new and used for the T800 & T900 chassis.
I'm not sure you can even buy GM service lit on paper for the K2 & T1 chassis.