The GE boxcabs were built in two batches, as Nos 6-10 in 1929 and 1930. These were built by GE using Winton engines purchased from EMC, so carried serial numbers for both. They were later repowered with Superior diesels. The UP photo is actually related - the lead and second to last units are GE, the other are EMD (successor to EMC), just a difference of around 3/4 of a century of technology.
The boxcabs were built for United Fruit Company (better known as Chiquita) for their Chiriqui Land Company subsidiary in Panama which operated on the Pacific coast adjacent to the Costa Rican border hauling bananas to Puerto Armuelles for export, and well as passengers and supplies to various labor camps and company towns. United Fruit renumbered the locomotives on their various railroads around 1967, so most of those on that division simply had 700 added to their original number (which is why the later photo shows it with both the number 9 and X709). This division was notable with the plantations having been opened about 1929 and the railroad was primarily diesel operated (only 2 maybe 3 steam locomotives) until operations ceased due to the end of banana growing in the area circa 1992. The line also used part of the state owned Chiriqui Railroad, and I recall had some lines in Costa Rica. United Fruit built the FC del Sur in Costa Rica at 42" gauge, and the lines were rearranged and regauged to keep them on the sides of their respective borders. There was a short section of 36/42 dual gauge where the railroads interchanged at the border. Regardless of distance, they hauled the bananas to their respective ports.
The boxcabs were documented in operation as late as 1979 when there were 15 engines on the roster. The boxcabs, as well as the Alcos, may have lasted untilt he end of operations. The Chiriqui Land Company had two separate divisions that had no physical connections, the other one exporting through the Caribbean port of Almirante, this division renamed Bocas Fruit Company. After the closure of the Southern or Armuelles division, some engines were transferred. The 720 at Sumpter Valley and another 50 ton bought by RDC and sent to CDN in Mozambique (unconfirmed if ever regauged and used) are the only known survivors from this division assuming all the remaining CLC/BFC diesels in Panama were scrapped.
The biggest issue in finding appropriate narrow gauge diesels in North America is simple - too many of the narrow gauge operations did not survive to be dieselized. Consider the known "road" type diesel electrics:
The two USATC diesels that test on the DRGW - both scrapped.
Southen Pacific #1 - last known to be still in existence, long out of service.
A few Hawaiian engines - 15 and 19 on CATS
US Gypsum - 1203 at Durango, the two 54 tons belonging to Ashby's, the DL535E
White Pass & Yukon
US Potash - all diesel engines scrapped
Newfoundland did well, but was 42" gauge. The main railroad, Grand Falls Central and a connecting industrial all had road diesels.
Mexico seemed to only have the EMD GA-8 - I think two or three survive on display.
Except for USG, are all the narrow gauge industrials in North America now gone? There is still some limited use in mining and tunneling (along with new engines). I'm not aware of any steel mills still using narrow gauge - they are either closed, manufacturing changes eliminated the NG or have switch to wheeled vehicles. It really doesn't matter as steel mill engines are the worst choice for heavy grade road operations.
