The right header has all four...
The right header has all four tubes on a common flange, and it went in from below without any hang-ups.
While the header decision was made, we had to consider the options on the exhaust system. Having been around the car hobby for years, the terms "bolt-on" and "do-it-yourself" are met with a certain degree of cynicism. We've come to learn that often "bolt-on" means you can bolt it on, but you better have a MIG welder and die grinder handy when you do it (we do). Somehow, at first blush, we were hesitant to bolt in our own 3-inch exhaust system. After all, while we have about as well-equipped of a workshop as can be imagined, we don't have a hydraulic pipe bender. There was always Dick, our local muffler guy. But for that to work, we always have to go in prepared for a fight. Tell good old Dick you'd like even 2 1/2-inch tubes all the way back, and he'll look at you sideways like a rattlesnake, and curse you up and down. "Two and a half-inch? It'll never clear the suspension....It's too tight to the tank....There won't be enough back pressure to make any horsepower....What the heck you bring me those junk mufflers for? What you need are a set of these." And on and on. We could only imagine the agony of requesting a full 3-inch system to the tips in an A-Body.
Last year at Carlisle we watched the guys from tti install a 3-inch system on the spot in a '71 B-Body. Man, it really did bolt in. Having witnessed that performance, we were more than ready to try it for ourselves on the Duster. We'd get the full 3-inch system we were after, with smooth die-formed mandrel bends rather than muffler-shop compression bends, real heavy-duty isolating hangers instead of the welded-on steel straps and rubber doughnuts, and it would save the open header drive into town to the muffler shop. Best of all, we wouldn't have to knock heads with our buddy Dick at the muffler shop. Our only concern was our lack of a car lift, but we had some tall jackstands and the willingness to give it a try. We ordered tti's full 3-inch system, which includes an "H" crossover. DynoMax SuperTurbo mufflers were specified, which are reasonably priced and reasonably quiet, while substantial in flow. Our exhaust system came in boxes from tti just before high noon, and by sundown the Duster was on the road.

With the headers bolted in,...

With the headers bolted in, we moved on to the exhaust system-first the flange adapters at the headers, followed by the two head pipes. The system clamps in place, although we kept it loose until the complete system was in, just in case some adjustment was required. Note that the header collector flanges are clocked so there's no bolt ear pointing down, maximizing ground clearance. Nice details we appreciate.

The right header fits neatly...

The right header fits neatly to the block. Typically, this isn't the problem side on A-Body vehicles.

Next, the mufflers. We went...

Next, the mufflers. We went with DynoMax SuperTurbos-the standard mufflers tti recommends. They clamped to the head pipes up front, and at the rear with tti's beefy hangers.

The tti kit came with these...

The tti kit came with these OE-style tailpipe hangers, which we bolted to existing holes in the framerail. The tailpipes are the most critical part of the system for fit, especially with a 3-inch system.

The huge tailpipes proved...

The huge tailpipes proved to be bent perfectly for the chassis, snaking between the frame and the shocks, then around the gas tank with clearance to spare. We got the job done ourselves at home in no time, and didn't have to put up with Dick.