The end that plugs into the car's harness has just leads and not 880 plugs? that's cheap. I have ordered from DDM before and they are plug and play and comes with the 880 plug. I can tell
you that if they are not wired properly they will not last long. I did the same thing like you and used pig tails with electrical tape and if I even flick the connection they will short.
Best bet is to use the actual 880 plug. I had good luck with using the additional harness that connects to the battery instead.