The square plug that is needed from the Spyder to trailer is also available at your local NAPA AUTO PARTS.
If they do not have in stock, they can order.
I paid ± $5.00 for mine and it worked 100%
I use the mail part of the plug as a "cap" for the trailer when the trailer is not in use. (Attached elsewhere to the trailer)
The part number from NAPA is 755-1570