Yes the carbs have changed from the first batch, The easiest way to tell the difference is to look at the idle adjustment screw. When the engine is in a 1/8 buggy the old carbs the idle screw was facing the front of the car or the flywheel side of the car. The new carbs have the idle screw placed at the rear of the carb. facing the rear of the car or the cooling head side of the carb. As far as needles go, both carbs use the same needles and needle seats. Also the new carbs. no longer use the plastic sleeve into the crankcase and that was the weak link of the old carb but now that its fixed there have been no carb. issues.