You better check the gear set in the rear drive box. The 5.9 turns at a slightly faster rpm than a combine with the 8.3 and I think the gear ratio in the box is different to keep the combine speed the same to function correctly. Radiator and air cleaner are also different so make sure you get those along with the 8.3. Pistons in a 8.3 are different for a combine than a tractor or a highway tractor due to different load cycle and rpm operation, ring lands are different position. Combines average 100% load cycle were a highway application averages 60% load cycle. Put a 5.9 or 8.3 Cummins in your combine that was built for a highway application it will not survive very long.
You may want to check with a ag salvage yard. I know a guy who does a far bit of business with Combine world in Saskatchewan, http://www.combineworld.com/ I don't know where your at, so I hope this helps
Thanks, I didn't think about a truck engine being different. The burned engines I found are from a 7140 and 2388. Yes, the PTO gears would need changed if I used a 2200 rpm engine, most every thing else is the same, starter, radiator, flywheel and air cleaner. Would need engine mounts, fan, fan shroud and hoses.