Ok im workin on a 50hp 1988 evinrude. i was looking to replace the orifice on the top of the carb and i dont know which one to buy. they sell ORIFICE, Idle, No. 40 - 40 models and ORIFICE, Idle, Std., No. 36 - 50 models. i dont know the difference but if yall know that would be a big help. also...