The tire pressure sensors for the 2001 are more expensove than the 2002 and newer. GM does not track the battery life in their TPS, so you may buy a "pig in a poke" from GM and have the batteries fail soon after they are installed. I understand that Napa tracks their battery installation and guarantees them, so you may want to buy from them. One of the CAC sponsors, Corvette Center, can get them for you if can't get them yourself. Rik at Corvette Center says they work with the GM system, and you can replace all 4 of them or individually, and since they work independently, you can use both GM and Napa at the same time. I plan to use Napa once mine go out or when I change to M Pilots. I believe the 2001s will cost about $100 each.
Barrett