A little less plug-and-play, but a little more grassroots: a coolant temp sensor from a 4.2L Trailblazer fits in place of the oil drain plug on the factory wet-sump pan. The connector is different, so you'll need to adapt it, but it reads on the same scale as all late-model GM coolant and oil temp sensors like you mentioned. This is how I've had my car set up for a couple years, since I used the factory temp sensor location for a turbo oil feed, and it's been working great.