Question - do the new GLS come with a rear 7 pin connector so I can plug in a travel trailer?

 

Do you mean the current model? That would be the X167 platform, and the X167 would be a good place to ask the question. Or Google "GLS owner's manual" and it will take you to M-B's online owner's manuals where it will be detailed.

 

If you mean new X166 yes they do.

 

if you have factory installed “tow hitch” listed on your vin option list it is there. If not see other threads on x166 tow hitch about after market options. Quite a few low priced hitches from Curt et. al. To be used with wireless brake controllers.