Its been a few years since I last seen this. What happens is the operator either knowingly or not heads home with the tractor really low in trans oil. Usually 10-20 gal. low. This fella headed home because he had a bad leak and and knew it was getting low in oil. When roading the tractor in 4th gear everything is spinning fast throwing off lube oil of course. When the oil level is so low and there is no oil to sling around only bad things will happen in those tractors and this is what normally happens. The gears spinning on the pinion shaft run dry and try to weld themselves to the shaft. A lube line was added to later tractors and can be added to older units. I have not seen a tractor equipped with the pinion lube line do this. The pic shows the heated scored gears and shift collar sitting next to normal ones. The brg. pic is the RH diff. carrier brg. On 12+1370's and 2390's this brg. should be replaced if it is removed for whatever reason. In this area we have seen these fail over the years. 1570's+2590's have a larger RH diff brg. and I have not seen a failure on those. Rod.