Pete, he will be able to identify the parts from your pic now. The only way to identify the valve he has is to open the tank and look at the tag on the valve body and part# stamped on the relief valves. The seal causing the problem is the small one in the RH end of the valve in center pic. Those pic are a great help.
Later Bob

Thanks tremendously to both of you for the help. My serial number is 60A11345. Sunday afternoon I noticed the line running from the lift spool area to the tilt relief valve and became suspicious. After reading these posts I was confident and took the valve apart. One of the "pistons" on the right end was stuck in its bore, bad anough I had to resort to a screwdriver and hammer to get it out. I have yet to find any remnants of an oring seal, so I assume it is completely gone. Hopefully I can get a few parts and get it back together one afternnon this week and see what happens. The spare valve/tank assembly I have, from a lever steer 955, doesn't have the extra line, and I was trying to disassemble it to see how things worked to diagnose the one on the tractor to make sure I could fix it with the least disassembly. Finally I did notice the extra line on one and looked for the parts book. Now I think I am on the right track. Thanks again to all. Now could anyone help with any rain (.2" here in the last 60 days) or some cooler temps (100+ for 12 days straight, one day of 99, and now back to 100+). I was worth a try.
Tony

Hi CatDog,
Glad to see you got the info:D
By sr. # 60A10220 the differential tilt relief conversion group became standard and the tank & valve group you have is a 2J7886.

That's the problem with going by the Service Manual.....it doesn't reflect the changes that come later in the production sequence....eg they show none of this in the hydraulic schematic.

Bob.....always enjoy teaming up with you on these toughies:D

Yes Pete these are the good ones.
CatDog, get some crocus cloth and polish those slugs and the spool up real good untill everything slides freely. Reseal as much of the valve as you can now. You have a lot of hard flattened seals in there and they will cause drifting. Get right back to the mounting and then do the lines that connect on the outside. A lot of work but well worth it while you have it apart.
Later Bob

This has tekan a while, but persistence pays off, and I just wanted to post to let everyone know it is fixed, and so maybe someone with the same problem can search the archives one day and find the solution. I did as suggested and pulled the differential valve apart and polished everything and put in new o-rings. I put everything back together and now the boom wouldn't hold at all, whether tilting the bucket or not. Now I was postive I was on the right track. I took everything back apart and rechecked the valve. The spools slid freely, but not sloppy loose. It is possible I have something missing entirely, but I am not able to relate my valve to the diagram very well. So, I took the old style relief valve off the old hydraulic unit I had, installed it, and plugged the hole in the top of the lift valve housing/make up valve which went to the tilt relief/differential valve, and put everything back together. Now everything works and holds perfectly, no matter what is done. Something in the differential valve is just not right. A friend has a later model 955H parts tractor I will try to borrow the differential valve out of to disassemble and compare to mine to see what is missing, in the wrong place, or worn out. For now I can be careful and use it as it is. I'll probably wait until winter to take it back apart. While it was in the shop disabled, I did replace the bucket pivot pins and bushings, and will probablt rebush the rest of the tilt linkage not that I see what a difference it makes. Thanks to both of you for the assistance/guidance. I'd probably still be keeping Caterpillar in business by buying tank gaskets, taking it apart and putting it back together.

Hi CatDog,
Glad to hear you got it going, even if you did have to revert to the previous model valve. Kinda wondered how you made out....thanks for the status update.
Be interested to hear what you find when you get around to comparing the newer valve. I imagine by now you could disassemble/reassemble the valve in your sleep:D

The 6H9691 seal is what was causing the problem. Did you replace that one and get everything back the same?
Later Bob

I did replace that seal, as well and polishing the sleeves. The problem is, I am pretty sure it has been apart before, and my internal parts don't look just like the ones in the parts book for my serial number. I think there may have been some parts swapping in the past and everything isn't working together. At this point my patience was wearing thin as well. I'll give it a rest, then start again taking the differential valve apart and comparing to the parts book and I'm sure I'll either find something missing or that doesn't belong. In the meantime it works better than it has since I've owned it. Do either of you know about a sluggish transmission or torque converter? Up until an hour or so of use, I can stop it by pressing one steering pedal in second gear. To make a turn I either have to "pump" the pedal, or shift back to low, and then it slows down. It never stops pulling, just is sluggish. I've changed the transmission filter with genuine Cat and helped, but only slightly. Everything has relatively new and clean 30 wt oil. Thanks again.
Tont

I wonder if the steering clutches are getting fully released? if they are not it will be like dragging the brakes. Also make sure your throttle linkage is giving you full travel of the lever on the governor. It takes about 5 times the power to drive the track turning as going straight. It should turn in high gear though. Study the other valve closely as you take it apart.
Later Bob