Here's where search and the TMs help. A quick look at the proper TM (-20P) will show 10045847 as the part number. This is a GM/AC Delco part number. Now Google it or, if you do a search on this site for 10045847, you'll find several threads covering this.
Search the number on Ebay, too. I'm sure there there too.
A cold sensor should read at least 800 ohms.
Also, read all the threads that come up with a search for the number. There is an O rileys number listed(may be others) in one of the threads.
btw, the -20 TM has step by step testing procedures for the entire GP system.(pretty much what I have been telling you, but more systematic).