I just took apart a core motor that had all brown ramps. The part number on the ramps was ground off. My guess is some discounter was selling out of spec brown ramps as black. Most would not know the difference. Easy to see height difference when black and brown are side by side.

john

I have used all brown ramps when I needed to relax the chains a little. Factory parts sold in the aftermarket were required to grind off part numbers, but not always.