Skimming through some back issues I just obtained, I was surprised to find in the May 1974 issue of Railroad Model Craftsman that William Johann had won the RMC/Dremel Kitbashing Award for a Watchung Valley HO EMD SD35! He was active in a HO (multi-scale, really) club in southern California and built the model for use there. The article mentions that he prefers to model in OO and closes with this paragraph.

The concept of being able to enjoy modeling in more than one scale due to an association of modelers seems to be an excellent idea for the many hobbyists who, for one reason or another, have yet to settle on a single scale or gauge. In this instance, the motivation was sufficient to prompt a modeler to not only join in the fun but to construct a modern hood unit by kitbashing which was not otherwise commercially available.

The model itself was constructed using two GP35 bodies and the drive and some body parts from a SDP40. This photo I believe shows the model on his layout in 1983. A late version of his layout was dual scale, with HO visible on the top level and OO on the lower at this point.

I know he made similar models in OO from Athearn parts that were based on an EMD SDL39. It was a lightweight diesel for branch line use, built on shorter than standard wheelbase six axle trucks that could be approximated in OO with HO trucks. The result is a unit that looks rather like a small SD40. I have often thought about trying my hand at that one, and someday I may.