there is know problems with the diff. the reason they are different is because the diff in the truggy/buggy were and ARE the same ones out of the big bad monster truck the genesis/nemesis and thats why they are so beafy it is very hard to break a gear in these diffs and on top of that i no guys that run mugen jammin ect and the changing ring/pinion gears all the tim i race alot every weekend and practice during the week and i havent had one problem with my diffs and its been months and a driver from headrushhobbies been running the same diffs in the matrix for a year now (of constant weekly racing) and still has no problem and to top it off i just check my GREASE in my diffs in the buggy(matrix ofcourse) and it still perfect and its been 3 months about 16 races and there still SMOOTH as a knife going through butter.........so where evr you this "matrix diff problems" if probally that someone didnt know how to set the diffs up and they where just having problems either that or they dont know what there talking about and just wanna "hate" on the diffs