New Holland tn55 to tn65 conversion?

[bguinn450]

I have a TN55 with only 120hrs on it and need a bit more power. The TN65 has roughly 10 more PTO HP, which is a 22% improvement which I could use. After looking at a lot of capacities and dimensions, and more than a few part numbers, I am convinced the only difference between the two models is some form of fuel restrictor that limits the fuel flow, thus limiting the power. Neither unit is turbo, unlike the TN75, which is quite different in many engine internals and elsewhere, beyond just the thermal reactor.

Does anyone know what the difference is, and whether it is feasible to do a part swap and get me the extra power?

Thanks

Bill