Re: Further RG F-unit Q

Thanks to all who took a crack at answering. Looks like this'll have to remain a mystery for the time being, though Andy's comment does give some support to the idea that there was some technical reason behind the setup.
Mike, the CZ was a special train to me, growing up in the western suburbs of Colorado a couple of blocks from the Burlington mainline. Even in the later years, the CZ trainset and motive power was kept first rate - it was an odd train that went out with some sort of mixed set.
I'll never forget how disgusted I was with some of the mixed consists that went out of Chicago during the short-lived "California Service" period after the WP dropped out, and before the Amtrak changeover. When I moved to Colorado in '71, I was beyond thrilled to find that some of the best of the CZ lived on on the Rio Grande. My rides on the RG Zephyr are cherished memories.
Oh, and Greg, I always like to hear about what you've got in the pipeline, and have never felt that I was being "sold". Sounds like some interesting stuff coming up.
Thanks again to all,
Scott