Can someone help me identify this muffler? I could not find a part number on it. Reviewing pictures online, the 914-6, early 911, and even 912 look very similar. Are there measurements I can take to confirm? I don't have an assembled car to trial fit it on.

Did I mention it is hanging about 10 feet up on a wall with headers attached? Not certain if the headers are meant for the muffler. I can pull down if necessary.
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Looks like an aftermarket lre 74 911 / 914-6 muffler. The exhaust tip does not look like a stock muffler. Desireable two in one out type. Does it rattle when you shake it? Should be worth good money to the right buyer

Looks like the Leistritz muffler I have which has a 1969 date code...the one on the bottom....Leistritz and the Bischoff mufflers were factory installed....you can usually find a date code and model # stamped in on the bottom of the factory muffler....the 911 models tip have a downward and outward angle....the 914-6 model tip is more straight backward. You can see the the tip angle better on the 1972 Bischoff muffler on the top and the tip is a smooth pipe like most mufflers.

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The date code is usually located on the bottom... on the side opposite the outlet tip and near the inlet pipe
Your muffler looks in pretty good shape so you should be able to find the numbers.

Great info John ,the 911 muffler is a non fit due to tail pipe angle with a stock rear valance , PO supplied 911 one had the conversion pipe welded on but rather large sorted a stainless tip modified to fit ,looks overkill but not loud .
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Not sure about the crimped bend on the pic supplied as not seen that before ,however if this one Dennis has proves be ok and the factory chrome tip fits it should be fine .
Not like you can pick and choose on a genuine unit unless you have a very fat cash supply ,don't expect to many NOS units around ? .
Cheers.

reproduction early 64-73 911

Good eye John. Thanks for your suggestion regarding date code and model. I took another pass and found this obscured by a lot of dust.
901.011.08/04 70
901/1

I guess this makes it a Leistritz for 911/12 from April 1970.

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I'm surprised to see such a wrinkled tailpipe on an OE Leistritz.
It is 911 only. 912s are quite different.

OEM '6' Leistritz shown. Found on bottom of muffler toward tailpipe side