There is a ball mount with 1-7/8 inch, 2 inch and 2-5/16 inch hitch balls, though the Channel Style Adjustable Ball Mount # C45900 you asked about does not have a separate 1-7/8 inch hitch ball attachment.
Instead, I recommend checking out the Curt Multi-Ball Adjustable Ball Mount for 2" Trailer Hitches # D900 which has a 1-7/8 inch hitch ball with 6,000 lb capacity, a 2 inch hitch ball with 7,500 lb capacity and a 2-5/8 inch hitch ball with 10,000 lb capacity. This ball mount has a maximum... view full answer...
Go To Results