I didnt have one, so I bought this solid state module on ebay that makes any relay a latching relay. It turns ground off and on with a pulsed switch. If you have a constant voltage to the relay, it will turn on and latch, turn of when pulsed again or interupted by the reverse switch…..it woked pretty good at 1st, but now it has malfunctioned. I havent found the time to figure the problem out yet, maybe I need to mount the relay isolated…or it is a wireing problem, but I think it will work…..old style latching relays are hard to find….Mike S.