I was just looking through some of the posts and saw this. I worked alot on the FG25ST-11. They had a problem blowing the pinion seals alot. Komatsu had a tech bulletin to correct the problem. It required installing a differntial bypass. You put a fitting in the side of the tranny down low at the point of the screen. then a fitting in the fill plug on the differntial and a hose between the two. You have to drain the gear oil out of the differential and refill it with tranny fluid. The fluid is pushed back into the tranny when the diff gets too full.