8 1/2 years old? I figure this problem didn't just occur. You have been dealing with it for a long time, is my guess.
Please do not give this dog to a stranger, the dog deserves to spend the remainder of his days with you.
I think it is your responsiblity to do whatever neccesary to fulfil the commitment you made, when you got him.
Too many dogs are throw aways, and an 8 1/2 year old dog with some problems will never have a chance, it will end up being euthanized by the new owners, because of behavior problems.
I believe you should stand up and take responsiblity for the life you took responsiblity for so many years ago.
I would never think about raising a pup, then 8 years later, decide to toss him. When you get a pup, it should be for the life of the dog!!!
This dog will do far better with you, than any other family that are strangers.
And considering you contributed to the dogs agressive behavior, by not socializing him enough at a young age, you should be the one to deal with his behaviors. Not some unsuspecting new family, just trying to save your throw away.
Take responsiblity and do something about it. Training, classes, or whatever might help. Try it and do whatever else you have been doing for all these years, just to get by.
Julie.