Those 6-wheelers that survived in traffic into the 1960s were overwhelmingly ex-MGWR - built like tanks. Yet, after the last actual passenger-carrying ones were withdrawn finally in 1963, the few (2?) passenger brakes which lingered on were ex GSWR, as this example.
Thus, these two were the only six wheelers ever to wear black'n'tan. I forget the number of this one, which was still running in 1967, but the other was 1888-built 69, now undergoing an extremely lengthy restoration at Downpatrick and conversion to a brake first. For DCDR members of tender years here, this is what 69 looked like before arriving at the DCDR.
These two vans were also, perhaps uniquely, fitted with gangways possibly by the GSR, or maybe more likely CIE. 69 was withdrawn in mid / late 60s too.