Can anyone tell me some details on the stock rear end that is under my "84 Mustang? Its has a 3.8V6/Auto trans. I'm pretty sure its a 7.5 rather than a 8.8. I'd imagine that the gear ratio is pretty conservative since it was a grandpamobile. A local junkyard has a 89-91 4cy/auto mustang with a rear end ripe for the picking. I'm thinking that its probably got a lower gear set and maybe the later model 8.8. I know the 8.8 is beefier but I don't know when they started or the particulars.