I need to know where exactly is the rack n pinion? How much to repair or replace on 1999 Buick Century

I have bought new tires 3 times in one year, a shade tree mechanic said it was due to the rack n pinion. Not sure of the spelling but thats what he said.

Asked by for the 1999 Buick Century
Three sets of tires in one year is crazy.Is it an alignment issue? The steering "toe set" is set by adjusting the length of the tie rod ends attached to the steering rack. Rack replacement is just under three hours work and parts could run between $325 to $650 depending where parts are sourced. Google steering rack image you will see good illustrations.