According to the D&H PA4 book, the original GE governor was adapted to the 251. Apparently the D&H mechanical department developed a fuel limiter circuit.
As best I can determine, the GE 17MG governor was used on the Alco 12-244 and 16-244 engines, possibly the only governor type fitted to those types in railroad service. Then it was used on the early Alco 12-251 and 16-251 engines in railroad service, eventually displaced by the Woodward PG. But the 6-251 appears to have used the Woodward PG from the start. GE also used the 17MG on some of its Cooper Bessemer FVL-12T engine installations on export locomotives, although others had the Woodward UG8.
Cheers,