Steve, with the older (non-Stealth)_ BLI locos you will have to get creative and use one of the wired-in decoders. You will have either to cut the connectors from the wire harness and splice the decoder wires, or get some JST connector with pigtail wires and splice the decoder's wires to the pigtails. Be warned that I recall some older Paragon decoders used common negative (not typical DCC common positive "blue") for lights. If that is the case then you will have to deal with that too. BLI just wanted to be different from the DCC standard.
I'm also wondering if BLI would sell you just the "stealth" circuit board which you could likely then use with the existing wire harnesses. Those boards have standard Nex18 DCC interface to plug in any Next18 decoder. Maybe tell them that you will swap them your Paragon 4 decoder boards for the stealth adapter?
