Matt, the curved upper links make that a QAxxB model, the reason the upper links are curved are for use on a 82 series for more clearance for the grill casting. It should work just fine on a 1650 with the links curved up or down. The B models also used a wider drive pulley, 5/8" instead of the 3/8" that your 1650 would require. It's possible that yours has had the pulley changed OR it's really a QAxxA and has just had the upper links changed out for the curved links.