I have built a lot of winches for the 3pt system. Mostly pto units, but electric and hydraulic ones also.
Using a truck rearend is not the answer. It will way to fast to be usable and unless you shorten the axles as much as possible they will be to far to one side to winch effectively. Your winch needs to pull from centerline of your pulling unit.
I had some winches built with 9.1 gearing. With the 540 pto speed that was plenty fast. If it were me to do it again with just this and that to build with, I would use a bush hog gearbox, post hole digger box as a primary drive and run a sprocket to a drum with a ratchet brake on it. You can drop the ratios by the different sprockets and by putting a ratchet dog/pawl on the other side of the drum you can lock it. When released you should be able to pull the cable out with little effort. Everything would turn includint the driveshaft, but with that little bit of tension it will keep the drum from fouling. Just an idea. Was my next build if I wear out what I have now.