Thanks for your response Pax8! My training skills are a tad rusty but since having him they are coming back. My other dogs were a 110Lb Lab and a Aust Shep.... so I know about the brains and the brawn. Your right, this guy is smart. But sitting is very hard on him due to spinal issues and atrophy in his legs.
Poor boy! I'm glad he's found a comfortable home!
It doesn't necessarily have to be a sit. The more important part of that is the stay part. I usually try to teach a sit or a down because they are less likely to try to move forward. Is a down more comfortable for him? If not, a stand stay would work as well, it is just much easier for them to break a stay from a standing position.