For a short period in early 90s 14x units were banned from working with 155/6/8 units there was some kind of incident but not sure what but it didn't last long
The 151s were mentioned earlier I believe these could also work with 150001/2 when the 150s were new. This because when they were built both classes had PBL air brakes , externally you could see a second air connection on the couplers
The 150s were rebuilt with westcode 3 step brakes as per the rest of the fleet
The two 150s had blanked spaces on the desk where the air train pipe gauges had been. Bit of a retrograde step really as with PBL a locomotive with a suitable adaptor coupling would have full control of the units brakes