I suspect the roll pin or &quot;part of&quot; is out of the P.T.O. &quot;hub&quot;. The hub is held on the shaft by a roll pin. The more I thought about the needles, I suppose they could've been stuck to the splines of the shaft when someone pulled the shaft out for a repair or other maintenance.

I've scanned images from my I.T. manual showing transmission, differential, and P.T.O. shaft for a reference.

The P.T.O shaft passes thru the countershaft. The P.T.O. shaft is supported at the front and rear with needle bearings. These are items 73 at the rear and item 78 at the front. These needles could be from the countershaft rear bearing or item 73. If they fell out for whatever reason, they would also end up in the rear compartment keeping the roll pin company. The roll pin is item 11. 

Could this cause your noise? Maybe. These pieces may just be &quot;trash&quot; left over from something else fixed previously. 

If you need any images or pages from my manual or assistance in pulling your top cover off give me a p.m. with details and I'll help if I can.