The 4x4 truck models have a stronger case that uses a stout cast alum converter cover, and can be built with a normal tailshaft and output yoke. The rv model they are talking about is called a turbo 475 I think. Many if not all have a huge drum parking brake on the output shaft. The main internal difference is the gears are straight cut rather than helical, so they make less end thrust, and should last longer. But a good offroad transmission guy (Alger, A&S Trans in Phx) told me he doesn't see a difference in life with the straight gears. All are pretty good, but avoid ones from the 1960's. You can't go too far wrong with a 2wd model from an 80's 1 ton pickup with a fixed output yoke. I see them on craigslist all the time. I have three and havent paid more than $100 yet.
Noise, A straight cut gear in the rear end would make your ears bleed
philofab - What is hypoid offset? Hypoid gear oil is the only thing that comes to mind and was under the impression it reduces froathing of the oil.
Check your gear pattern sounds to me like the pinion is not "IN" far enough or the pinion bearings don't have the proper preload at any rate the gears are all ready toast.
I willl find out if they are toast when I swap the spool out for a locker in a few weeks. I haven't driven the truck very much so the gears might not be toast just worn a little uneven. I can hope right.
Scottm and philofab - Thanks for the explanation, I've noticed different offsets but never gave it any thought. Any numbers regarding efficiency loss vs. teeth strength? I now might have another reason other than weight to run a Toyota 8" in my next project since I only plan to have 200 hp.