Will an exhaust system for a 71-74 Eldorado (without the cat) fit my car? No emissions testing in Indiana.
Possibly a good question. Seems like at one time I remember 71-72 being its own thing then 73-74. For 73 there were slight changes to the frame and engine/trans mounts made to accommodate the impact bumpers. Was that just a slight bend that was different or a hangar in a different spot? So aftermarket just made a movable hangar or included both bends? Or is what is often the case where they kinda make it in the middle so it doesn't really fit either perfectly? My guess is it can be made to work but don't expect a perfect bolt in deal.
I want to say that the passenger side manifold connection was slightly different depending on if it had the flapper valve or not and if that was there changed year to year also. It wasn't a it was there till this year then gone I think they came and went a few times in this era. Historically speaking the pipes off the engine were not available aftermarket, replacement systems tended to start after those pipes. One reason is there is enough heat up there that those sections didn't tend to rust out as fast.
Also note if what you are looking at is a dual system and you want it to sound stock that is very tall order to get 2 big enough quiet mufflers tucked up in there nice and the rear axle level control valve linkage often is in the way. What tends to happen is you end up with fairly small mufflers and louder which is fine if that is what you are going for or kinda a mess where they hang down kinda low. Remember most aftermarket exhaust is designed around a 302-351 ish engine in much lighter rigs so the typical muffler on one of those cars can be quiet till you get on it. That doesn't work with our cars, the larger displacement and having to get more car rolling often gets us into that loud mode with just normal driving. Again fine if that is what you are going for but will be very annoying of you want more of a factory sound.