I have a 2005 QC that I installed 3.73 gears in over a year ago. I have had no problems at all. I get about 1 more mpg in city driving and 2.5 better on the hiway. The total cost installed was under $600. I tow trailers with it on occasion but usually only about 2 to 4 thousand pounds. I did not notice that much difference in performance.