I dont think FL is "up" for CP, but I think he travels for work...lol. The cross over is a passage that connects the exh ports of cylinders (IIRC) #4 and #5. So some exhaust gasses can travel under the choke housing and heat it up good. The down side is, it adds heat to the intake itself, and that can rob a little power in some engines. The other bad news is most mopar chokes rely on only that heat to function properly and open all the way. The choke pull off is a vaccum pod on the carb (in the pic above I think) that "pulls" the choke plate open as the car is being driven, even when the choke coil has not fully warmed, and the plate has not fully opened. Otherwise, the car wouldnt run at all above an idle until the choke was open 100%. If it goes bad, the car will run rich until it warms fully. It's common for the vaccum pods to get a pinhole and not hold vaccum any more. If you remove the hose, and compress the diaphram on the pod, then place your finger over the nipple's end, you 'll know if the diaphram is good when you release the diaphram/linkage side. If it holds in the retracted position, the rubber is intact. If it extends back out with the nipple covered, it's got a hole.
