Welcome to the forum 1965JetfliteV143 !
Check the deck colors and style for year built or post your data plate.
The picture posted on the ad was hard to see numbers ...
OR ...
During the 60's, Glastron HIN's had six digits, and the the third
number from the left was the year. If the hull number on the outside of the transom is missing
or not legible, try looking on the underside of the dash near the steering column...There
often was a hidden one there. "
You can find product brochures here ..
https://www.glastron.com/us/catalogs-and-product-informationMotor brand would have depended on what brand the dealer sold, and holes drilled for a Merc would have been different from a Johnson / Evinrude motor.
Your transom would be a 20 inch (Long shaft).