Well where to start. I have a 2017 mustang Gt premium mustang. Standard equipped with a 3:15 gear ratio. 8.8” carrier, 34 spline. I took it to a trans/differential shop and got a phone call stating, “the top of the pinion head is rubbing on the carrier, this is the first time I’ve ever experienced this”. Everywhere said the 4:11 Yukon gears were compatible and for some reason they are not fitting. Anyone have a solution/ answer as to why I’m having this problem???