I am looking to overhaul the engine in a D6. I was told it was a 9u from the guy I bought it off of. I was told by the cat dealer that the serial # was on the back left corner of the crawler but it has a cable unit covering it up. They also told me there is a plate on the engine, but that plate has been broken off. I was wondering if there was any other way to ID this crawler. Thanks, Josh

The rear ID tag is not covered by the rear cable unit.
If it's there it would be high on the left hand corner looking at rear of tractor.
Sometimes the sr. no. is stamped into the housing under the normal tag location.
As far as it being a 9U, that's easy. The 9U is the wide gauge version (74 inches from sprocket centers)
If all the ID's are missing it is possible to approximate the model age by eyeballing the tractor and its accessories. As far as rebuilding the engine, the D318 is pretty standard in terms of normal wear parts.

You should found too the serie number on left side motor under the fuel pump near pan but not easy.

Thanks Gemdozer,
Went and checked and both mine are stamped quite clearly. The stamping is vertical on the block oil pan flange just under the fuel transfer pump about 2nd pan bolt back. Can't remember having to go look for it at this location before. The D4's (at least some) are also stamped along this same flange, but further back.

Do you have any good parts outlets for the D318? I'm not sure what I need yet, It runs but uses alot of oil! Thanks for the help.

I have some 318 use parts.