Read the attached link post #17 contains links to some useful information.
I agree with the response by Hohenwald although I feel #2 and #3 deserve some explanation rather than just a no answer.
FOR #2 Never assume what another TT's coupler height is and that yours will be the same although they may be close.
Make sure that the TV and the TV are both level. Then measure from the ground to the top of the coupler (or to the top if the inside of the coupler) The difference will only be the thickness of the metal. NEXT measure the height of the ball on the TV and adjust the height so it is the same or as close to the same as the measurement of the TT. You will want to use a adjustable ball mount on the TV.
IF the JAYCO spec sheet shows a coupler height of 25,5 inches then preset you TV's ball height to the same.
#3 Once the TT and TV are hooked up you will get some squat You will now adjust your spring bars/equalizer bars to remove this squat and to get the TV and TT back to being level. That is if you are using a WD hitch setup.
However in looking at the specs on the TT you are getting I doubt that you will be using a WD hitch or that you will have very much squat on a truck