The '66 Olds L69 setup used on 442's used the same Rochester carbs as the Pontiac in '66 only. All three carbs had the same casting numbers between Olds and Pontiac. Olds ran a slotted rod linkage piece to the front carb to actuate the secondary throttles, Pontiac also used a slotted rod, but to the rear carb.
The question I have relates to the center carb. The photos I've seen of the Olds Tri-Carb setups have ported vacuum off the center carb routed to the vacuum advance on the distributor. The vacuum fitting is located on the center carb passenger side toward the front. All the '66 Pontiac Tripowers I've seen and owned use manifold vacuum for the distributor advance taken off the base of the front carb. On Pontiac Tripowers prior to '66, ported vacuum was used for automatic cars and manifold vacuum was used for stickshift cars.
Does anyone know about this?