G'day Dan, We were able to use a '96 R-72, so not exactly a step down!! Cummins thought it was in the fuel side of things, and replaced injectors etc. looking for a dead miss in no. 6 at up to about 1500 RPM. The engine ran fine at full song, perhaps minus a few horsepower, but the crops weren't good enough this year to test it. The turbo was undamaged, manifolds stayed on until she cried enough. Thanks, silver aussie