Dog shock collar recommendations?

Before you guys say this is inhumane, I already know but I am at my wit's end. I own a 75% wolf, 25% alaskan malamute mixed breed. He comes above my waist (I'm 5'3) and weighs somewhere in the 150-250 range, I don't know exact for sure. My problem is that he's a runner. We live out in the country but we don't have a fence or that shock field thing around our yard, so we normally hook him up to a long chain in our yard. Without fail he chews through or slips out of whatever we hook him up with. He had a nice $60 harness and thick metal chain and he chewed through the harness and broke the chain. As a last resort I'm asking for recommendations on shock collars that we can use to train him to stay in our yard and/or make him stop when we're chasing him when he's on the loose. He's gotten loose about 10-15 times in the 3 months we've had him and we can't even get him back until he decides to come home a day later because he's too fast. Neighbors are threatening to shoot him and we really don't want to get rid of him