The #1 answer to this on *any* 1998 - 2000 Taco nowadays would be frame rust.
If you're not familiar with the 1995.5 - 2000 frame rust / extended warranty campaign that began in 2008, check the sticky thread at the top of the Exterior section.
Other than that, I can't think of any widespread mechanical issues relating to a 2000 5-lug Regular Cab.
If you're not familiar with the 1995.5 - 2000 frame rust / extended warranty campaign that began in 2008, check the sticky thread at the top of the Exterior section.
Other than that, I can't think of any widespread mechanical issues relating to a 2000 5-lug Regular Cab.