I can understand your frustrations as irritating and never-ending. When I built my 190 up I replaced the differential with one stronger and with a limited slip and used one from a 92 Corvette ZR-1. The original diff from my 1984 190/2.2 diesel is lying around in my shop looking for a new home. I don't know what your current ratio is but mine is a 3.42 and probably a little lower than yours which would help low end performance. It's for sale for $100/ FOB from Charlotte, NC.