JDavis...Hi there. I have a '98 LS400 in outstanding shape...with ~157K Miles. I live in S. TX...the timing belt has not been changed...but I bought da parts & will do it myself after it warms up a little more...post-chilly winter. Personally...my primary concerns are: the age on the belt, interference engine, and of course higher mileage. Got an independent estimate for ~$950 w/out water pump & $1200 with W/P. Will do myself for ~$175.00. Did my 3.5RL last year...have an AAS in Auto Tech...but not an active mechanic.
My advise: If ya can't do it yourself...take your car to a good NAPA, ASE, etc certified shop & save $1,000, or so. Good Luck.