Beat Cop.

This video is notable because it features the first ever appearance by tattooed tough guy Donnie Russo, who would go on to become one of the nastiest muscle-heads in the business. On the other hand, even discounting Russo's debut this one is well worth a look. The action is strictly solo, but it's not your standard jerk-off video by any measure - these guys are built and they are really into what they're doing.