A handful of MOW cars and the executive cars should be all that saw actual "Conrail" paint. The track geometry train falls into this group as well. By 1976 what passenger service was still run by Conrail was paid for by other entities, so far as I know the cars in those services got those entities logos when repainted.
The CNY NRHS had a couple of baggage cars used into Conrail in specialized service - they were rigged up for hauling jet motors for GE, or some such thing (it could be they were just company cars hauling engines for the snow-jets and such too, I can't remember). Of the pair, one was still in grey NYC paint, the other was a PC repaint on a New Haven car (this car was burned by vandals and scrapped).
