1971 Gravely Commercial 450 Transmission-PTO-

[slappy]

I have a 1971 Gravely 450 Commercial Lawn and Garden Tactor. I have been experiencing problems related to the transmission and PTO. Initially I began to have problems with the tractor maintaining its ground speed in the 2nd Gear-High range. The tractor seemed to "surge" into gear and go fast but then would do the opposite and slow down and at times barely move. I adjusted the jam nuts on the transmission shift lever linkage per the manual and this seemed to help for awhile, but then it started to have similar symptoms once again. I have been thinking that I need a transmission rebuild. I called one of the Gravely dealers and they indicated there are a couple of clutch plates in the transmission that could be worn. I have a parts diagram of the transmission but don't see any clutch plates listed. Can anyone familiar with this type of unit tell me what the normal "wear" parts would be that need replacing? Or have any comments or suggestions for repair? Problem # 2 relates to the PTO. When the PTO is engaged to the mower deck it sporadically makes a clanking-grinding noise and the PTO lever vibrates and almost wants to jump out of the IN position. I opened up the PTO and found the thrust bearing in 2 pieces and am assuming this is the problem. If I replace the thrust bearing should this correct the problem or perhaps this is a symptom of other problems?