JerryJ,
I believe you have a 2" coupler. I have 2" on my 1983 T-1550.
I actually picked the trailer up from buyer and then went to a Meet and Greet in Up-State New York with the trailer pulled on my 1 7/8 " ball, a total of about 300 miles before I realized the coupler was for a 2" ball. It pulled very well and I had no issues, although I don't recommend it.
My 1996 T-2053 is a 2 5/16" coupler. So I have 3 trailers all with different couplers and each with a different hitch set-up.
The 1 7/8" is a Harbor Freight light utility trailer, not a travel trailer.
I'll check my coupler on the T-1550 as I think under the paint on the coupler may be the ball size. I'm pretty sure I saw it on the T-2053 as when I picked that trailer up I came prepared for 2" and 2 5/16".