The C403J is the same as the other half of the C400P that’ll come on the WH00125 harness. If you try the 403J in the square holes for the left and right C400Ps you’ll find that they are not a good fit. Clips do not engage as they should. Couple options. Use the connectors that’ll come with the WH-00125 and pro seal in the square hole to secure them, once you are attaching wings. Or you can order the original Molex plugs which were originally used for that C400P hole. Molex part # 03-09-2091. They are now obsolete from Molex and that’s how this all started. However, if you can’t source them in the US, they have some at Farmtronics in Canada. Their part # is F-J0017. You’ll need 2, one for each side, and everything going forward will match up. Third option (not my favourite) is to abandon the plastic housings once It’s time to attach wings. You could de-pin them one at a time, slide heat shrink over wire, connect pins then heat shrink em.