Ok i done a conversion on a s10 4X4 this weekend. We where going to put new plugs in and when I pulled #6 and #8 There was what looked like to me was a adapter for a compression tester. We didnt put them back in. Have yall ran in to this before. I have been working on cars and trucks for years. I have never seen this before. Here are some pics http://s891.photobucket.com/albums/ac117/Roscoe-01/S10%20V8/