A few thoughts:
GE appeared to have a fairly soft changeover process from one design iteration to the next. For example, Comilog Gabon was receiving the “long-nose” U15C variant, and with equalized trucks, for a couple of years or so after other roads were receiving the “short-nose” variant, usually with non-equalized trucks. So the production of high-short hood units after 1964, if that’s what customers wanted, wouldn’t be too surprising.
Before its U15C fleet, Comilog acquired U13Cs from 1960 through 1968. The early examples of course were high-hood. But whether it changed to low-hood for its later deliveries I don’t know. I’ll recheck data on hand, but I suspect that they don’t answer the question.
I recall seeing a 1965 specification for the U13C, that showed both a low-nose and unequalized trucks, so GE had done the design work by then. Actually, I am not sure when the low nose variants were first catalogued. The first built were the U20C model in 1964, and in fact no high-hood versions of the U20C were built, even though it had been catalogued. My guess is 1963 or early 1964 for the catalogue change.
With the low-nose U13C, the trucks were moved backwards from a previous symmetrical distribution, so that the front frame overhang became 14 inches greater than the rear overhang.
When it came to operating manuals for the GE export Universals, GE appeared to issue all of generic, model-specific railroad-specific varieties.
In my small collection is a railroad- and model-specific issue for the New Zealand Railways U10B, even though it was essentially the standard version. Another covers the 8-cylinder U18C with 26L brake, no railroad mentioned but surely it applied to the Indonesian version. And an issue for the 12-cylinder short-nose U20C covers a specific version with 221 000 lb weight (baseline was 198 000 lb or thereabouts, right-hand drive, supervisory transition control (that basically allowed forestalling of any transition), and 28-LV-1 brakes but no dynamic brake. I imagine that it was for one of the sub-equatorial African roads, but just which I haven’t worked out.
So in that context, a special issue for the Chilean low-short hood (long-nose) U13C would not be so surprising.
Generally, when it comes to the GE export Universals, there is only so far one can go using “external” information and observations. I think it would require access to GE’s detailed records and builder’s photographs to develop a comprehensive history.
Cheers,
GE GEJ-3802A Universal fc.jpg
GE U20C GEJ-3879A 1980-04 fc.jpg
GE U18C GEJ-6392 1983-02 fc.jpg