Division Point made 3 of the RDC 4 models. Rather rare models, the RDC 3 was a little more prolific with some 25 pieces in various roads. I have a B&M sadly always wanted the RDC 2 in CNW Jack imported and only seen one in photos. WooSong Brass Model really knocked it out of the park with the model still the best Budd body ever made in any scale. Jack was unclear with me on the RDC as it was a unique project for sure. I will see if I can find some photos and I have a copy of the pro-forma from WooSung Model and DVP with an inventory of produced RDCs. The RDC 4 was much shorter than the 1-3.
Wasatch Model (Roger Lewis) might top it for detail or more likely match it with the Ex-Key California Zephyr we will see but the drawings say it should. On the other hand Sunset's RDC is a close second for detailing and are excellent models as well.
I have no idea if Scott did any of the odd RDCs like the 4. I have never seen one, only the common RDCs like the RDC 1 from Sunset. I have seen the DVP RDC 4 in person we had one come through Caboose Hobbies back around 2010; dang it I wish I bought it. I priced it at 1300 as I recall and it didn't last long!