Nephew has a Bron tracked undercarriage with a cross axle. It was the first prototype built by RWF Bron manufacturing out of Woodstock Ontario. Its 20 years old but built super heavy. It uses all standard type bearings and the tracks are from a 9000 series Case Quad.
The cross axle gives it a 120" wheel base center to center. It's 8" sq. with fish plates top and bottom
What's is it worth?
My suggestion is for someone else looking to add tracks to a grain cart or perhaps someone building a strip til tool bar. It is heavy enough for 25T or a 900-1000 bu. cart.