It is surpisingly difficult to find information online about the ball size and height for the Jayco Flight 7' wide trailer series. The manual from Jayco is absurdly general, and while ball size and height are specified on Jayco's website for some trailer years it wasn't specified for 2020 models for some reason. Basically most answers involve looking at the tag on the tounge of the trailer to find out, but since I can't do that yet until I pick up the trailer the other option calling the company to find out (although some people have reported not getting a good answer from doing that either). It also doesn't help that most people online are looking for info about the Jayco 8' wide trailers, which seem like they may have a different ball size. It appears as though there are only three standard ball sizes, 1-7/8", 2", and 2-5/8". It looks like the 8' trailers use the 2-5/8" ball, while the 7' trailers may use the 2" ball.
This expert at e-trailer points out that convertable balls are a purchasable product that can be made to do any of the sizes: https://www.etrailer.com/question-335215.html
This is a question from somebody who has an SLX 195 which is probably a 8' trailer. However his question includes the tidbit that his coupler height is 18.5" which I think I've seen elsewhere. That's a pretty high height considering that my hitch height is 11" for the Sienna! The answer to this question is notable because it contains links to info about all kinds of other things that I've never heard of before, like a trailer weight tester and a weight distribution shank. https://www.etrailer.com/question-523734.html
Here's my 174BH on a different website that at least has the courtesy to specify the ball size. This has it at 2". Also this page has the best pictures I've ever encountered of this model: https://rv.ruckify.com/2019-JAYCO-JAYFLIGHT-SLX-174BH/
