Lots of NWC T-5s came with gear oil.
I can't remember who it was here on the Stovebolt, but they owned an S10 with a NWC T5. They went out and looked at the owners manual in the glove box to check what tranny fluid was required. The owner's manual said Dexron II for the NWC T5. I have heard that the really early T5s used gear oil. Can't go wrong with Dex/Merc for a NWC T5.
