The biggest difference is the Bosch P7100 (aka the P-Pump). The P-pump was added to the engine so the 5.9L would meet the new emission standards that came out in 1994. The P7100 produces higher injection pressures and in turn decreases the particulate matter produced in the cylinder and going out of the tailpipe.
If your 5.9L Cummins diesel engine is not running properly or you need 5.9L aftermarket upgrade parts, ProSource can help. We have all the diesel engine parts you need to get your Cummins 5.9L running smoothly and performing better than ever.