2001 JD 4300 SRT 4WD tractor with 750 hours with 420 front end loader and 47 backhoe, purchased 2 weeks ago. I used it to move piles of dirt and debris from timber property that was clear cut in 2017. I worked slowly knowing stumps would be present. I have hit a number of stumps over the 10 hours of operation before my failure. AGAIN, these stump strikes were under low power to keep from damaging equipment or operator (me). The last stump I hit caused the tractor to sound like it was going to fall apart on the very spot. I dumped the bucket and headed for home 1/2 mile away (leaving tractor risked losing tractor). I rode home in mid range gears and the noise the tractor generated was enough to drown out the engine noise. It was a very loud grating, grinding, scraping noise, it was enough noise to make me want to stop, but I had no other way to get it home. The noise only occurs when tractor is in motion, does not occur in neutral (new information below). First impression of noise was a dragging brake. First impression of location was generally under the seat, maybe somewhat forward, very difficult to pinpoint from the seat. The noise reduced by 75% by arrival at barn. No smoke or leaks. Assistant walking beside and around tractor while I drove said sound came from behind engine and in front of steering wheel (location of clutches). I confirmed same location as assistant drove. All 12 forward gears function, all 12 reverse gears work. With rear end raised, the sound does not exist in any gear. On the ground the sound is nearly gone but prevalent as tractor bounces on uneven ground. I would classify the sound as a grinding or grating sound, and from the seat it sounds like it is between the rear wheels. Hydraulic filter was removed and dissected and found to be completely clean, oil was a perfect clear amber, and filled to level in the sight glass. I have loosened the brake turnbuckles (thinking dragging brake) and the sound remains. Applying brakes during sound has no effect. Sound is equal in forward and reverse gears, always when bouncing even on slightly uneven ground. Based on conversations with heavy equipment repairmen, JD service staff, local guy that knows everything about tractors, I am inclined to believe the problem is in the clutches, but involvement of both clutches and lack of debris in filter steers me away from clutches. JD cannot diagnose my tractor for 4 weeks. While moving tractor in and out of barn to access other equipment today, I had opportunity to have the sound continue when tractor stopped moving. Holding brake to keep wheels in the spot where noise occurred I pressed clutch and sound intensified as the pedal reached end of stroke, lessened when released, remained with foot off clutch, and was able to repeat the same several times in that spot before I returned tractor to barn. Have not tried to reproduce that event again, it may have been a fluke since it had not occurred while stopped before. Again, this, in my mind, steers me to clutches. Thoughts? Ideas? Suggestions? Experience? Please, phrase any questions or suggestions in layman's terms, I am not a lifelong farmer and tractor owner, but equally, I am not a total novice. Working on the tractor myself does not frighten me, I am mechanically inclined, have the JD technical manual for this tractor and split my smaller (simpler) tractor last year which boosts my confidence. Thanks in advance, Jimmy.