My son just completed rebuilding the bottom end of a John Deere 2750 diesel. He is having a problem with the head the old one is "junk" He got a used head through the web yet it does not fit even though the the number check out. This tractor is a 1982 model 2750 yet the the engine cast no 239T indicates it is a 1984 model, go figure? The cast no retro fit to 219/239/439 for the head. The cast no on the original head is 5679 or 5779. He has contacted several places to get information and another possible head yet that was several days ago and no one has gotten back to him. Suggestions anyone, I probably screwed this up so much appreciated. We really need this tractor this time of year, thanks again.