The manifolds i have have the little screw on the botton for syncing them, that is the one you need for 69a s , i found out that the intakes are all the same, same angles and length and stud holes, only thing different is the hole for syncing, what i had to do what mount the manifolds first then put the right out of the microwave couplers on loosely , then the carbs, and still it was hard, but then went , then i tightened all the clamps down