If your doing a lunchbox locker you can do it yourself without messing with the R/P and can do the gears later. if your doing a locker than replaces the carrier then I would do them at the same time.
ARB is the best locker as far as selectables, as far as auto lockers/lunchboxes go, the aussie, spartan are some good and less pricey options, Detroit makes some good lockers as well, the loc right is their lunchbox I do believe.
I wouldn't lock your D35 if you wheel very hard, run tires bigger than 31, or both.
You can do a super kit and get away with a locker up to around 35s. a selectable is gona be easier on your axle because it is only applying force when in use, not constantly like with a lunchbox.
Ryan - A good eye, a light foot, and a smart rig. Bolt-ons are boring
I have a Detroit for a Dana 35 that I'll sell if you want to order a few parts to re-build it. I wont put it back in my rearend, I quit spending money on my 35c long ago. My avatar is my passenger side axle shaft just a couple of days after I snapped the driver side axle shaft........the locker is sitting in the garage with the passenger side spline still fused inside it.....
Don't bother putting any money into the Dana 35. Save the money you'd spend on regearing and buy a replacement 8.8 with 4.10 gearing, than just do the front. I don't know what tires you have now but 4.10 is sufficient (read good, not great) for up to 35s.
__________________ It's got a Willy's body, a Chevy engine, Ford axles, GM transmission, and Dodge steering components... it must be a Wrangler.