ehroof is right about the MIP, I liked the MIP clutches and springs on my traxxas ...


Also., I could be completely wrong about the "X" difference, but it 'seems' like the only difference was the same part being used for another vehicle - Example, I had a REVO and TMAXX at the same time, they were out of the part# but had a "X" which was listed for the "revo", but it was EXACTLY THE SAME PART (Not heavy duty) and worked great in my tmaxx ...

Like I said I could be wrong but I think (From my experience) that it is just a marker for another vehicle ...