We sold our Packmaster 2100C a few years ago, and I couldn't find any good pictures of the 6x6's, if you look close between the first and second belt, you can almost see the tapered end on top of the front axle. We welded small pieces on angle Iron to the front and back axles, drilled and lagged to 6x6. The 1"x4" plastic pieces screwed on top were tapered in front and back also, The lengths had to be just right that when the track turned forward or back, it would ride up level and not sag. Hope this makes sense!