I got the kit from "quick performance" in Iowa. The gentleman that rebuilt the 4L60E [for what amounted to the cost of a new one] took out the 2.41 open diff and put in this kit for $600. He's a sixty-year-old guy seems to know what he's doing... said he has built many rears, but would not install anything that wasn't OEM like. My priority was getting the car back on the road quickly before I smashed the windshield... I could have spent $2K on a new Ford 9" for g-body made by local speed shop, and bolted it in myself. Instead I spent $1,100 on new gears and labor to make the ratio more compatible with overdrive. I threw money at this project like a Democrat. Next build will be slower and less subcontracted.3.42 is the a good ratio for your combination. What's the story on the carrier/gearset? Did someone swap it in for you? Are the gears aftermarket (Punjab Gear Co.)?