Back in the 1970s SP and SSW had a batch of PC&F 50’ insulated boxcars with double plug Landis doors. Athearn has recently announced these in HO. On Railcarphotos I found an ATSF plug boxcar that has what I think is a Landis Plug door, ATSF #526263.
For whatever reason the Landis-type door didn’t catch on too well and cars with this type of door were/are very rare. Before I saw the pic of the ATSF car I assumed the only user for Landis door cars was SP/SSW.
The Penn Central Color Guide to Freight Equipment has a picture of boxcar 360321 with a Landis plug door. According to the photo caption this car was in series 360298 - 360447, and the cars were ex-NYC lot 112B cars, series 78550 - 78699. The caption notes that the Landis plug doors were “regarded as somewhat unreliable”.
Also, the Conrail Color Guide to Freight Equipment" shows two different cars with Landis doors, 230086 and 230121, both ex-NYC class 132B. The caption with the first photo says the cars were from NYC series 48360 - 48434, and that the cars had been built by Pacific Car and Foundry in 1967.
Maybe the Landis door was unique to PC&F built cars?