Here is an interesting article on 6-packs and options available.

Six Pack Rebop: Everything you need to know to rebuild the Six Pack on your 440 motor
BY RICHARD EHRENBERG. Copyright © 1989 Richard Ehrenberg. Used by permission of the author. Part numbers and availability may have changed since this article was written in 1989.

Just five short years ago, trying to replace a missing Six Pack setup for your 440 muscle Mopar was a frustrating experience. Manifolds and carbs were swap-meet-only items, usually commanding big bucks for less-than-pristine merchandise. In recent years, though, the situation has improved radically. Holley has seen fit to reintroduce enough carburetors (six, in all) to be usable for every application. Edeibrock also saw the restoration/nostalgia scene coming, so they retooled to reproduce their ’69-style aluminum manifold. The iron ’70 to ’71 manifold is gone forever, but since the ’69 piece is lighter, looks almost identical and works as well (or better), so what?

Many of the fuel line, linkage and air cleaner pieces are, incredibly, still available from Chrysler. Anything else you might need — including coil brackets, throttle cable and spring brackets — is readily available from the various repro merchants.

So, today you can do what would have been impossible just a few years ago: assemble a Six Pack setup using all-new components. But you will have to make some compromises. For example, although the air-cleaner base (“retainer,” in Mopar jargon) can still be had, the only one available are the later “splash shield” version. The shaker and ‘glass-hood variations are history (but, hey, there’s always the swap meets).

Holley is supplying the correct carbs for most ’71s, but for both ’69 and non-California ’70s, they’re substituting the ’70 California Evaporation Control System (ECS) carbs. This represents absolutely no problem as far as performance is concerned, with one exception: As our carb-specification chart shows, the replacement center carb for the ’70 to ’71 cars is a bit on the lean side, especially for fresh-air cars. You should, therefore, probably consider rejetting the center carb to stock specs (if not a step or two richer) for your make and model. The bit of extra fuel at cruise can help prevent the lean-surge condition that bothered some of these cars when they were new.

Holley jets are readily available, and it’s a five-minute job if performed before everything’s bolted together. If the gaskets aren’t reusable, be sure to use the new-style black cardboard gaskets (from Holley). They’re unaffected by today’s witches’ brew gasoline.

The ECS carbs (especially the center carb) cause one minor annoyance, though. They look a little different from the original, non-ECS carbs. However, there’s a simple remedy for that: Leave the air cleaner on at car shows!

If you’re using the Six Pack setup in a non-stock environment (e.g., 310-degree cam, open headers), the stock jetting will need to be tinkered for maximum performance. Your best reference for this is Mopar Performance’s Engine Performance Book, part No. P4349340. Holley also publishes and sells a whole library of tuneup, rework and parts books. An order form for these will be packed with the new carburetors.

One dark cloud has recently drifted into the otherwise-sunny parts scene: The air cleaner elements have been discontinued by both Mopar and Fram. We have word that Purolator is considering releasing the filters. Until then, the only alternative is the reusable K-N oil-bath element. Now this is really not a bad idea anyway, especially on the 1969 cars, where one rainstorm and your $30 paper element was trash!

In the last few years, we’ve seen Six Pack setups find their way onto everything from pickup trucks to luxury Cordobas. The Six Barrel was flexible, street-smart inductions setup that performed as well as it looked. Pop the hood at Burger King and crowds gather. Take your Six Pack and attack the Bowties!