Why? The OT-130 replaced the OT-26 in 1933, though I have no idea what the active service life was of either model. I do know that the OT-130 used a larger turret than the OT-26.
3 reasons:
1. The scenario book calls for OP-26's.
2. The OOBs I've seen many references to the OT-26, few OT-130's. There do not seem to have been very many present for these battles.
3. Flamethrower tanks should have red DF values.
As Jay tried to type, pass the info on. PG Nomahan, the boxed game, is still on the boxed burner, and it why PotE isn't a candidate for laser treatment.