Howdy friends, 

Just brought home my third D4 a couple weeks ago. Bought my first one 7U18985, three years ago. Two years ago I bought 5T1702 and a couple weeks ago I bought a 7U of which I am unsure the SN. Engine was swapped with a power unit engine and has Hyster winch on rear. I am hoping between the two 7U machines to make one good one. This one has nearly new tracks. Engine is stuck. Needs some work for sure. Has an engineered and stamped ROPS and what I believe is a cable control unit to run a scraper or...? Any feedback is appreciated. Has two piece trans cover. 

Mangoman

You've got something pretty good for starters as the tracks aren't bad and one can spend a fortune replacing and repairing them. If memory serves me right on the D4 new rails are about 3-5/8 and shot are about 3-1/4 so you have a lot of wear left. Stuck engine can run from disaster to easily fixed so hope it all works out the best.

Thats how it starts, one tractor a year for 3 years then before you know it's a couple a year.
Hard to tear apart one tractor to make another but it really is the way to go. You have a lot of good parts between your 2 7u tractors. Probably enough to get another 7u going, better start looking!
Rails look fat but the pin boss is starting to hit so you will want to check the rollers.
Good luck Nathan

THE CATERPILLAR PANDEMIC ..I call it the "The Caterpillar affection infection" and It is a real issue.🤔
The Cat affection infection is very easy to catch and is considered by some as terminal. Not so much as your are going to die from it but you will most likely die with it.... unless of course the other half finds the true number of Cats one has ...Just saying. 🤣😂🤣

Looking at it the 9S1 - up Power Units were D311 for Marine Applications.👍 Brass journals and lower RPMs.
D4N Hyster is integrated to the chassis so I'm not 100% sure where the second S/N tag is located. In Form 32504 it says on rear of transmission case, top left, but says nothing about the D4N Hyster attachment..I have seen where a D4 Hyster that are not integrated still have the S/N tag behind the bolted on wench.

If you want to take a 1200lb winch off its under the winch in the upper left hand corner of the rear of the transmission case.

what dan describes is also known as oldtractoritis and oldmachineryitis sadly this disease is incurable and can be fatal in extreme cases as other halves can become extremely jealous and shoot their partners due to lack of attention.

the only treatment is to surround sufferers with all forms of old machinery and the various publications of that nature. attend events at every opportunity and have a ever larger shed to hold the sufferers collection of what non enthusiasts refer to as old shit and wasted space.

Yes thanks for the input friends. I think I'm doing pretty good here with the parts on this machine alone well worth the cost. I will definitely remove the track frames and go through each, including the rollers. Amazingly the pony still turns despite not having a cover over the exhaust for many years. I think I will likely take the motor from 7U18985, give it a quick bottom end check and see if I can run it without a big to-do. I will likely trade the front cover as that one has a good crack in it. My better half decided she was better off without me last fall so I won't have to endure much opposition, although I probably should try to keep myself in check. I only have less than an acre and the driveway is getting plugged. My young man, Ezra (6) had a funny reaction to it when he first saw it. He looked at it long and hard, not saying anything. He looked and looked and looked, then asked what did I do to the dozer? He asked me what did I do to the cab (canopy is different) then I told him 😆 Ezra and his younger sister think it's pretty funny that I have a thing for this old "junk" and also old Homelite and McCulloch chainsaws. We all have a pretty good time. Looking forward to hopefully having time to get into it 🙂

something is off Fatdan as that should have a 315 not a d311. still a very nice looking dozer. rops s is nice but the stamp really mans nothing at it was built for a newer cat. that top add on cc unit on top of the winch was for a cable blade most where over head RG Letourneau for the war. thanks for sharing

Yes mog I would say its the 315. The ROPS was built for it. The company didn't know any better and went off the numbers on the side of the winch which for a D4 of that vintage is the "D4N" 9 times out of ten around here. It is built properly with supports under the fenders, tied into the main case. It was definitely not retrofitted. I suppose if I want, I could put it to work and if Worksafe showed up, it would be given the green flag. 
 

sorry about that
Thanks for the correction... I should have sited my sources cuz I don't remember which manual the information came from.
I must be slipping cuz that's the first thing they teach you in law school.🤔

UPDATE:
Found it .... I could blame it on my glasses but I couldn't find them