I have just made a deal on a D4C with the serial number of 40a4792 and I have had very limited success finding anything out about it. I would like to know the engine model of it so I can get a manual for it. I'd also like to know how to adjust the reverser so it doesn't grind from neutral to forward and reverse. It might be clutch adjustment because all of the clutches on it are out of adjustment. The main won't even overcenter. Thank you

The most useful manual is the operation and maintenance instructions(OMI). It has the instructions for adjustments to the clutch, interlock, and more.
I found this one on eBay cheap:
www.ebay.com/itm/405145501601
Craig
 

All D4Cs has D330 engine as far as I know

PDF DOWNLOAD FILES $20EA -- www.jensales.com/categories/caterpillar/d4c.html

Alright, thank you all for the help. Does that crawler have a Hydraulic main clutch? Also, how do I get a good factory manual for a d330? Every time I look I can't find any on ebay

How do I know what manual to get for the engine by itself? I had a 5u d2 and ended up getting the wrong manual for the motor so I'd like to be sure before I do that again. Is there an I'd tag that is different from the tractor serial number? I'd like to find all of the necessary books for it eventually.

www.jensales.com/content/ppp/caterpillar...ual-ct-s-d4-39a1.pdf

The D330a engine is covered in the 37/40Axxxx Service Manual. Separate D330a Engine Manuals cover the Industrial Engines.