3.73 Rear End

any V6 ranger or aerostar is supposed to have a 7.5" locking differential.

I am looking to do this too to improve my winter drivability.

Well, you can take the gears and the trak-lok out of a ranger or areostar, but you'll have to swap them into your housing because their housings won't work.

I Agree And Disagree....Most all Rangers from 84 92 or so came from the factory with a 7.5inch rear....not all came with a factory trac lock ie..posi..and there were several gear ratio options 3,55 3.73 4.10 offered but 3.73 is most popular...you have several options from this point if you are happy with your gear ratio as it stands and just want to go with a posi unit you can buy one that will install in place of spider gears only eliminating the need to set up the whole rear end gears.and only bout 250-300 bux for the part..i cant think of the manufacturers off hand but if you wanna go that route post and ill send up as much info as needed for that option.. NEXT you could go and find a 3.73 rear with a trac loc and pull carrier ring gear and pinon out of donor housing at this rate though i would highly recomend rebuilding the trac loc wich is almost a absolute must annd you will still have to get a set up kit and set the gears up.. this can be costly if you dont know how to set em up yourself..here is some info to help you read the gear ratio off of axle tag located on one of the diff cover bolts >>>>>>>>it will have several numbers and letters what you need to look for gear ratio markings and posi lettering here a generic example xxx3.7375xx or xx753.73Xx that would be a stock 373 rear no posi>>>> xx3ls7375xx 753ls73XX would be a posi 373 the LS is what your looking for in a posi type unit...www.therangerstation.com may have a better description of how to read em but thats the basics for ya hope it helps...Zach

3.73's

Best place to find a 3.73 locking diff with a housing that will bolt into your mustang is an 87/88 T-bird turbo coupe with an auto trans. They came with disc brakes but you don't have to use them. Your 85 Mustang axles and brakes will swap over to the t-bird housing.