1988 Chevy S-10 towing behind motor home

I have an old 1988 -2 wheel drive, Chevy S-10 pick up truck with a manual transmission that I want to tow behind my motor home.

Does anyone know the name of an auxiliary part item that fastens onto the back of a manual transmission that allows the back axle to free wheel without turning the gears in the transmission when the vehicle is being towed.

I was told it was “a transmission power shift”, but when I looked it up on googles, something else all together came up.

Could some one please tell me what the name brand of this auxiliary part is ?

Thanks.[img:c177bead14]http://www.2carpros.com/forum/automotive_pictures/162773_good_photo_of_S10_in_Alberta_2_1.jpg[/img:c177bead14]