no 8050 hyds, again! HELP!!!!

Last week while using my 8050, I turned off the main road and as I was stopping on a slope and grabbing the remote lever all at once, I noticed my drill did not raise.  Puzzled, I pulled the other remote lever, no sound of any pressure in the remote hyd system at all. Then I noticed that I had no steering, no power shift, nothing. I let the tractor roll to level ground, unhooked the drill and went and got another tractor to drag the 8050 out of the way.  When I got back ( approx 10 minutes), just for the heck of it, I started the 8050, the steering worked, the remotes worked and the trans worked. As I was pulling away from the drill I heard a very rattley type of sound (hard to explain, happened so fast) from underneath somewhere and the tractor stopped, I shut it off quickly and took the other tractor and dragged the 8050 out of the way.  Within minutes, I started the 8050 again and once more everything seemed to be working as it should, I very carefully drove it back to my shop. When I got to the shop I tried everything I could to try to get the torque limiter or transmission to slip or break, everything OK, remotes and steering OK. Used the tractor a few hours the next day, everything OK. Today as I was headed down the road, I noticed someone trying to pass me on a double yellow line, I gave the steering wheel a quick jerk to the right and slowed down, that is when I noticed all of a sudden, I had no steering, no transmission, no hyd again. Had to drag it back to the shop tonight and was getting ready to split it and check for bad torgue limiter, but decided to get other opinions. What do y'all think and why? Torque limiter, hyd pump drive coupler, any other ideas or suggestions on how to trouble shoot. Oh I forgot, 8400 hours, original owner, full of oil, filters changed regularly, and other tractor doing the dragging was AC. Thanks