my dad runs a dual case setup with a 4cyl and he has been wheeling it for about 10yrs now and its been fine with a 21 spline setup and he has been on many trails from simple like bald mtn to more extreem as in dusey ershm and swamp and has had no problem. i run a single case 21 spline 470 with a 4cyl and as the same have had no problems. btw im running 35s and he is running 37s. just my 2cents
