There are a bunch. My father happens to have a Snap-On unit (thanks to a find he got on eBay). It supports up to 2001 (but I found I can easily use it for ODB-II reads, it's the functional tests it's limited on, but I can fake it out to work 100% with my '04 Monte since from the tools perspective, nothing has changed since '01).

I'd look for one that can:
- Do sensor reads
- Read current and various historical codes (the snap-on can read codes since last cleared, codes thrown this ignition cycle, codes currently active).
- And can clear codes
- For ABS sensors, if it can record a minute of data is nice!

And all that is pretty much generic ODB-II stuff (so not sure how big an issue it is for "updates").

 

Well I finally had a chance to hook it up to a scan tool. Temp would reach like 226 and the fans would come on. Looks like the gauge in the cluster is bad.