Tahoe 2003 5.3 liter with Auxiliary rear heat controls located in the front overhead ceiling: I am having difficulty identifying the correct replacement part for the Auxiliary Rear Temperature Blend Door Actuator. Dealer said that the original part number #15201869 is no longer available, and that there have been 3 subsequent changes. The latest change listed was PN was ACDelco 15832319 , discontinued. Advanced Auto listed Motormite 604-100 as exact fit, $40. Ordered it. Installed it. My experience was incorrect PIN pattern: Failed . Internet shows prices from $20 -$160 for exact fits. What part is correct?