the 1990s Trek 8000 came with Shimano Deore DX/LX components.
it's a square-taper BB. Use a crank puller shown below (TL-FC10.jpg) to remove the other crank.
remove the BB cups using a BB tool (BBT-2.jpg). remember that the drive side has a left-hand thread.
ParkTool has the complete drill on bottotm bracket maintenance.