I just keep looking at the photos at this link and what they show doesn't make any sense to me. Take a look at the Hotchkiss and direct connection connectors and I think you will see what I mean. If there is no plate. I would suggest that you shape a piece of metal and weld it to the crossmember before you but the connector to it and weld it to strengthen that member. You are going to put a bunch of stress on it.
