Looking at what i belive to be a 951c this weekend. I have a serial number 86j3469 which would make me belive its a 3304, and a 1974 model. But the owner says he thinks is a D330. He also states it needs a head or head gasket which would make more sense if it is a d330. Hoping for a 3304 since parts are much easier to come by.
Easy way to tell is to look at the injection pump. Is it a forged body scroll or sleeve metering?
Provided that the engine is original then per the machine Serial Number it will be a 3304. The change from the D330 engine happened from 86J2598-Up. The engine S/N plate should read 78Pxxxxx. The machine data plate should look somewhat like the image below. If the engine was a D330 then it would carry a plate showing the same Serial Number as the machine in which it was orignally installed. So if this loader has had a D330 transplant at some point look for a S/N plate on the engine block with something other than 78Pxxxxx stamped on it.