I have an Earl's adapter. The ports are 3/8 NPT. I don't think the adapter ports to the AN lines fittings are leaking. I rewrapped them with teflon tape.
The pipe thread(including the BST) are tapered. But it will probably leak if sealant is not used. The leak probably came from the oil port that feeds the passenger turbo. I had liquid teflon on it. But the heat and pressure probably ruined it.