I converted Lionel's 8580 Illinois Central F3 with dual Pullmor motors to digital using one of ERR's conversion kits. These conversions are easy and very straightforward (I don't put smoke units in diesel units).
Even though it was successful I wasn't happy with the engine's performance. This was not an issue with the ERR kit but with the Pullmor motors.
I eventually sent the engine off to Timko Repair; who did a fantastic job replacing the AC motors with DC can motors. Now the F3 runs as smooth as ever.