Markwz11

I bought a 74 Cutlass Supreme a few mos. ago (knowing that I would be replacing the exhaust) and have run into a problem. When I ask the Midas/Merlin people about my exhaust, they only come up with "single" exhaust. I've done a little research and have seen that 74 did have the option of duals. I've already found a few minor things that the "little 'ol man" I bought it from Fudged The Truth on, but for the most part, it's been as described. Is there a way, maybe thru ViN# or something, that I can find out if my particular car came with the "optional" dual exhaust? If so, there seem to be many aftermarkets available... as long as it was duals from the factory. It has duals right now. Thanks for any help. Oh yah, it has the original 350 Rocket.
Mark

lunaboy

I believe the 5th letter in vin will tell you. M for L34 350 with factory duals.

Markwz11

So when I'm asked, "is it a Vin-K or Vin-M"... this is what they are referring to? It's definitely a Vin-M. There is no K in the entire VIN#. Does this mean K is Single Exhaust and M is Dual Exhaust? I told the Midas dude that it was a Vin-M and when he looked it up, it still showed Single Exhaust.

CRUZN 66

X2.... The actual optional code is N-10, which should appear on the build sheet if you happen to have it..........

Markwz11

No Build-Sheet... any other thoughts? Would it be on the body plate that's up on the Firewall under the hood, just below the Passenger Wiper Blade? I know this plate had many number codes...one of which give the paint color code.

oldcutlass

Does it really matter what the vin# states to put duals on it?

Fun71

Agreed. Who cares what it came with from the factory?

FYI, original dual exhaust cars had a flat block-off plate where the crossover pipe bolted up. These were unavailable for a while, and many times folks would just cut the crossoverpipe and weld it closed when converting to duals instead of trying to locate a block-off plate. But as stated, who cares at this point?

Markwz11

I was simply trying to figure out if there was an easy way to find out if my car came with factory dual exhaust, so I could order Bolt-On Replacements if at all possible. I like to do my own work when at all possible.

No, it doesn't matter what the vin# says in order to put duals on it. It doesn't matter what the vin# says in order to swap the motor, trans, rear-end or even change the color of the paint, but that's not what I was asking.

I was told that this was the place to join if I really wanted to become knowledgable of my Olds Cutlass... I'm not so sure. Thank you to those who truly tried to help me out.

texxas

The Midas guy's reference is wrong. Vin K is single exhaust 350 in 1974. Vin M is dual exhaust 350 as stated previously.
If you get a chance, let's see some pictures of your car.

Markwz11

Thanks "texxas"... Mine is definitely a Vin-M.

oldcutlass

We were not trying to belittle you. All any vendor needed to know to put duals on your car is the year, engine size, and diameter tube you wanted to go with. Most of us do our own work, although a custom exhaust installed (not at a Midas store) is usually the same price as you ordering all the parts and installing them yourself.

coppercutlass

Most midas stores in the area for me sell flowmaster or offer a performance line .

Fun71

Well what we meant, as oldcutlass stated, is that it doesn't matter what the car came with. You can put duals on a car that came with single exhaust and it would be the same part numbers as replacing duals on a car that originally had them. The passengers side pipe would be the same between single and dual exhaust cars, then the single exhaust crossover pipe would be deleted (and the crossover port capped) and a drivers side pipe would be installed.

ELY442

I use to have a 74 but it was in brown. I bought my car to Meineke (same as Midas) and they did my dual exhaust with no problems. I ask for 2 1/4" pipes and use their own mufflers. I used Dynomax from Walker but it sucks too much gas so i switch it to a Cadillac mufflers (what a difference when it comes to saving gas and noise). Your transmission cross member should have the double hump for the dual exhaust. Meineke type in their computer and it printed out where to bend the pipes.

joe_padavano

To clarify, the VIN does NOT tell you the exhaust type directly. It DOES tell you the engine code in 1974. The engine codes indirectly tell you the type of exhaust. As noted, VIN M is a 350 with dual exhaust. VIN U is a 455 with dual exhaust.

Markwz11

Thanks. I'm leaning toward a Flowmaster Exhaust. They've been great on other vehicles and did not like the Thrush Set I bought once before. I'll stick with what I have good experience with.

texxas

Nice car, is that original paint?

oldsmobiledave

Are you telling us that Walker Dynomax mufflers casued a significant decrease in fuel economy & then you switched to a Cadillac? muffler & the fuel economy increased appreciably?. Really? Really? Please tell us more about this. I am all ears! Also is this Cadillac the GM car maker or a muffler brand named Cadillac? Care to share some flow & backpressure numbers on these mufflers versus the Walker Dynomax ones that were "using more fuel"?

Markwz11

Thanks. Yes it is. It has just under 35K miles. Brake/Fuel lines have been replaced along with many "tune up" items... and believe it or not, everything works... even the 8Track.

ELY442

Yes this is what Im telling you. I drive my girlfriend to work every weekend and its an 1 hr drive. When i fill my gas tank up its takes a 1/2 tank to get to where she works. By the time i get home the tank is empty and i have to fill it up again. I have a friend who use to work in Meineke and i told him to switch mufflers because it sucks a lot of gas. He told me that he will give me the same size mufflers that a Cadillac uses. So when i drive my girlfriend to work with those Cadillac mufflers, it only uses 1/4 tank. I dont have any flow & back pressure numbers. I just drive and tell you my point of view.

oldcutlass

I have Walkers on mine, I would like the part number of the ones you got so I can double my mileage.

oldsmobiledave

Exactly! there is NO WAY that changing mufflers results in a 100% increase in fuel economy. Something stinks with this logic.

ELY442

If you want the part number go to Meineke. I dont have the car no more.

ELY442

Nothing stinks. It happened to me ok?

z11375ss

Here we go again. I seem to remember a thread that went this way a while back. Mufflers don't double fuel mileage, let's make that clear right now.

redoldsman

I am sorry, if Cadillac mufflers doubled mileage, we would have heard by now and everybody in the country would be running them. I would put a set on my V-10 Ford truck and then I would get 23.6 MPG. There are too many other variables to consider. It just ain't possible.