- Place wood chips in a bowl and set aside. 
- Pop tabs on beer cans and make 2 additional holes in each top using a church-key opener. 
- Pour half the beer from each can over the wood chips. Add additional beer or water to cover chips completely. 
- Soak wood chips for 1 hour, then drain. 
- Set up grill for indirect grilling and preheat to 350°F. 
- Sprinkle 1 teaspoon barbecue rub in neck cavity and 2 teaspoons in main cavity of each chicken. 
- Add 1 tablespoon barbecue rub to each half-full beer can (foaming is normal). 
- Season outside of each chicken with 2 tablespoons barbecue rub. 
- Stand beer cans on work surface. Hold each chicken upright and lower over can so it goes into main cavity. 
- Pull chicken legs forward to form a tripod base. Chicken should sit upright and stable. 
- Carefully transfer chickens to grill center over drip pan, away from direct heat. 
- Add wood chips: if using charcoal, toss half on each coal mound; if using gas, place in smoker box. 
- Grill chickens for approximately 1½ hours, maintaining 350°F temperature. 
- Cook until internal temperature reaches 165°F in thickest part of thigh. 
- Carefully transfer birds to platter in upright position. 
- Lift birds off cans to carve and discard cans.