Any project that involves John Deere is a headache.
A couple of years ago I decided to restore a crawler. I have a Cat 30, but wanted something a bit more modern and that could be of use around here at the farm.
Saw the first JD 40 at a guys house with the engine disasssembled, crankshaft laying on the track, and a broken block. Tried to buy it but he wouldn't sell. Six months or so later he shows up and says $600. So the thing arrived. I started looking for an engine and meanwhile dove into the remainder of the carcass with the intention of beginning the restoration. The first thing I found was the left bull gear case was broken and welded and broken again due to failure of the main differential carrier bearing. STOP. Out of the shop it went. Last fall I heard of another complete running crawler for sale outside of Las Vegas. Same model, only a few serial numbers apart. Negotiated and bought it for $1000. 600 mile round trip and then it was here.
The first crawler has a 3 roller undercarriage. The latest is a 4 roller undercarriage. 1st oops! The guy told me the tracks were shot and he was correct, as they spun the sprockets in the rails so that omitted using them. The plan was to use it as a parts source for the 1st (3 roller) tractor. Well I cut off the track on the left side to access the bull gear case and lo and behold! Uncle Deere changed the casting sometime between the serial numbers of the two tractors. STOP. Out of the shop it went.
Now I got two of the **** things and over $1600 invested.
A couple of months later I got to thinking and looking at both of them and figured I need to reverse the proceedure. Use the 2nd one as the base tractor, install the 3 roller track frame under it and junk the 1st one.
So I stuck my neck out again for another $610 for new engine parts.
Gonna be a pricy project. I'll keep this updated.
Dave

Dave,

Keep us posted on this.  A couple good things is that parts are easy to find for these tractors and you can even get a lot of parts from the JD dealer.

Bad part is that JD tractor parts from the dealer or private parties are not cheap.

George

This sounds like a very interesting story unfolding--please keep us posted as you make progress!  Fortunately for me I have noticed that Deere seems pretty reasonable for parts for my 40 year old combine. I have ordered on Fri afternoon and had parts Sat morning for just a couple bucks freight. It seems all Deere dealers are now part of chains/franchises. Six or eight of them have now gone together in our "area" I called up before lunch one Fri. needing parts and they had them brought in before quitting time from another dealership. Evidently they have parts/equipment runners that run daily between the dealerships.