I had to read up on what a CF7 actually was. (EMD's converted F7 used on the ATSF until 1984). How long did Amtrak use them?
Now that I know I want one too!
I would prefer the Sd70.
Not sure how long Amtrak used them. I last saw one in the early 1990's. They were used in the coach yards to move stuff around.
I can't remember what engines EMD wanted Santa Fe to trade the F-units in for (I think GP35's but don't quote me) but Santa Fe estimated that they could save $90,000 per unit converting them rather than trading them in. Across 200+ units, that was a healthy chunk of change. I had the data somewhere on what it actually cost per unit. I think the actual number was 233 of them from F-unit A's on roster. The B-units remained in service as boosters for a while. The CF7's were sold off in the late 1980's and I've personally seen them on the LA Junction (ATSF Subsidiary that had four of them) in the mid-1990's.
Realistically, Atlas could use the GP7 frame to support the superstructure -- they're pretty close. The prototypes had modified frames because the carbody of the F-units actually partially supported the locomotive like a uni-body car.
At first glance, a CF7 looks like an odd-ball Geep, since few outside of ATSF foamers would recognize it for what it really is, but it's one of those locomotives that's historically significant and in some ways is the precursor of the locomotive remanufacturing industry.