99 was the year venturi was going boom and then bust, venturi to my knowledge only used
aerotech units. FMI should be completely ruled out. a quick easy way to tell if its a petersen
vortex is the blower will be near the back behind the rear wheels under the truck, the brackets that hold it will be banged and bent up from dragging the ground in ever case I have seen, they also only put them in bering trucks, so you should be able to tell without even looking inside