If your MH is on a Freightliner chassis it is probably prewired. Give them a call.
My 04 was wired, the plug under the dash was a bare to find.
Does your dolly have electric brakes?
04 Horizon QD, 12 Ford Flex, Excalibar, Brake-Pro, ,, Winter Texan, RVin! since 1974
Norm, Donna & Tinker Kat 74 MGB-GT, 75 MGB, 01 Z3
Life is a Timed Event, you only get One Go Around!