Well it kinda depends on where you live. If it is cold out i doubt i would use a 160 because your heater won't be as warm. I just called bumper to bumper and they only show one for a 1999 silverado 5.3. they said it is a 186 degree stat and it comes with new housing. I thought stock was 195 from GM but maybe it is 186. I think i want a 160 anyway!! I guess i will be checking out the sites that were listed earlier in this thread. Thanks guys!