I am wanting to put a limited slip rear end in my '68 coupe. I have a top loader 4 speed as the transmission. The rear end currently is stock. My door plate is missing and I really don't know what gear I am running. I believe it's a 8 inch rear end with a 2.90... I have been reading about the explorer rear swap. The ratio is 3.75... My father (also a mustang enthusiast) believes that will be too low for cruising on the highway... What are you running? I need some advice..