Can someone explain how do you tell whether your longtail is a high transom model or a low transom model? What is the key to this, I am thinking it is something in the motor bracket but I could be way off. thanks.

Measure from the bottom of the u joint to the end of the shaft. Most short transom longtails are less than 72"... using that method, if it's a little less than 72" that's because there's about 1 or 2 inches of shaft in the u joint. If it's considerably less like in the neighborhood of 60" it's a short transom.

It's simple. get a mud motor. shoot ducks in the face.

I thought most longtails were made for short transom?

Not entirely true. alot of places have an option on shaft length if you are ordering directly from them. For example backwater has a 59" and a 71". You need a longer one for a tall transom due to shaft and prop angle relative to the water line. I'm pretty sure backwater had the different shaft lengths listed as tall and short transom

It's simple. get a mud motor. shoot ducks in the face.