three at once....Help

Are you brining the breasts?  That can affect cooking times.  And, what temp do you want to cook the lamb to?  IT 135°, 145°, 155°, or 165°?  The turkey should be cooked to min. 165°.  And, do you have an approx. physical size or Qview?  And, what ext. temp your smoker?  I would guess around 3 hrs. myself, but with no visual, or temp, it would be hard to guesstimate.  Also, you want to put the lamb above the poultry otherwise drip contamination from the poultry. 

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