My diff. is shot and needs to be replaced. I was wondering if I could upgrade to a newer disc brake rear and how much trouble would I be looking at? What years could I use? Aside from the gear ratio needing to be the same (i have a 4x4) will I need to change the brake master cylinder and proportioning valve? Are the spring perches and shock mounts in the same location? Can I swap yokes to use my original driveshaft?