I wrote this article a couple of years back...but I do not know if I ever posted it on FABO or not, so the information may or may not be new to all readers.
I provide this information in reference to posts #5 (mine) and #12 asking about the straight through muffler design. (see picture below looking all the way straight through the muffler)
From my 65 Chrysler parts book dated May 1965 muffler listing for 1965 Valiant and Dart cars with 4bbl. carb w/powerpack:
2534467 Aluminized front muffler
2534468 Zinc coated front muffler
This is the original style, no-baffle early 273 HP Valiant, Dart and Barracuda replacement muffler. The first 273 HP cars came from the factory with a straight through exhaust flow muffler. Even with the rear resonator, this muffler produced excessively loud snap-crackle-pop exhaust notes when letting off the gas pedal, a sound that car magazine writers raved about in printed articles after road testing early A-body cars equipped with the 273 power pack engine. The inlet and outlet nipples on this muffler were centered in the ends of the muffler body. You can see straight through this muffler. After several months of production, Chrysler either on it’s own or from outside pressure, decided the sound was excessively loud and took steps to reduce the noise level.
My 1965 Chrysler parts book, dated March 1966, superseded the May 1965 version and list new and different part numbers for HP 273 muffler. The new numbers are 2660541 and 2660548 and this muffler is significantly different in construction.
It is a reverse flow, low restrictive muffler, meaning baffles inside the muffler reversed the flow of exhaust gases before sending them to the now off-center outlet pipe. The result is a significant reduction in noise level and eliminated the snap-crackle-pop found on early models.
A 1966 Chrysler parts book dated March 1967 shows the same 2660541 and 2660548 part numbers for the 1966 Valiant and Dart 273 HP application.
I have an NOS straight through unbaffled muffler on my 65 Formula S and can attest to it’s loud sound with snap-crackle-pop. My 66 Formula S has the later muffler and is significantly quieter and no crackle sound.
FABO members may or may not know that beginning in 1964, Chrysler Corp. established it’s own franchised automotive parts stores across the US. My part time college job in 1964 was at one of these new Mopar “Single Source Supply” stores. We sold a complete line of service parts for multi-make vehicles including Chrysler, Ford, GM, International, Jeep, and other foreign and domestic makes, all packaged with a Mopar logo. The stores were established to compete with other existing independent and franchised stores such as NAPA.
View attachment 1715655048View attachment 1715655049View attachment 1715655050
So what is this NM-8887 Mopar muffler? It is essentially an early 1965 273 HP replacement aftermarket front muffler packaged in a Mopar box and sold from one of these franchised Mopar parts stores. Note the label on the muffler box: “manufacturer no. 2534467, 2534468”. Purist take note: The NM-8887 muffler does not have a embossed Penstar, vendor number or date code stamped on it. On the other hand if a 273 HP muffler had been purchased from Chrysler Parts Division, the Chrysler dealer parts department would have ordered part number 2534467 (aluminized) or 2534468 (zinc coated) and the result would be a muffler with the Penstar and other codes stamped on it, but not a NM-8887 label.
I am fortunate to have some of the Mopar Parts line catalogs from the 1970’s (example Ignition, Belt and Hose, Brake, Exhaust , etc) which allowed me to identify the application for this NM-8788 muffler. If and when the NOS 2534468 muffler currently on my 65 Barracuda needs a replacement, this NM-8887 will do the replacing.
Here are two other examples of Mopar parts sold through “Single Source Supply” stores.
View attachment 1715655053
Here you see pictured a 1960’s Chrysler product application voltage regulator with the Mopar (CH-524) and the Chrysler engineering part number (2098300) printed on the box.
View attachment 1715655054
On the other hand, this particular Mopar regulator (DR-500) was erroneously described on eBay as fitting 1956-62 Chrysler, Dodge, DeSoto and Plymouth cars. Perhaps an easy mistake since looking closely at the cover, you can see the Chrysler penstar and corporate name prominently stamped on it. Actually it has no Chrysler application period…it is for 1960’s Rambler, Studebaker, Oldsmobile, International truck and other makes. Lesson: don’t mistakenly assume all “Mopar” parts have Chrysler Corp applications. Lots of NOS Chrysler parts may have been salvaged from closed after market “Single Source Supply” businesses.
I remember Mopar Single Source Suppy stores had prefixes on their Ignition Line parts that loosely indicated the application. For example ignition point part numbers DR-1V, CH-15V and FO-5V were all packaged in Mopar green boxes. DR for Delco Remy applications, CH for Chrysler applications and FO for Ford applications. Thus the DR-500 voltage regulator shown above had a Delco Remy application…not Chrylser or Ford.
I found it interesting also, that as counter guys, we had access to a cross reference book allowing us to cross reference a Chrysler engineering parts number to the Mopar number. For example muffler part number 2534467 and 2534468 both crossed to NM-8887 (NM prefix meant muffler). This cross referencing ability helped encourage and made it easier for Chrysler dealers to buy replacement parts from us by simply supplying us with the Chrysler number and we would cross it.
December 2020 note....I never quite finished the article. I always wanted to know the change over dates for the different muffler types but that information escaped me. Also, I never knew the resonators were once pained black, so thanks for that new-to-me info.
