This thread takes me back. Oh, the good old days...
To the OP, I would say, at least back in the day, you would need a 451m...[Link: ebay.com]
What I remember from the Fords is if the vehicle had keyless, it was negative trigger locks. If No keyless, then 5 wire (using the 451m)
Though I'm still foggy on what a "remote relay system" is. Is that a remote start? or a keyless entry system? Anyway, I remember pink/yellow and pink/green for locks.