Exhaust Question and Interchange Parts Numbers

[Samplingman]

First, does anyone have an online source for interchange part numbers, or perhaps can someone look this up for me?

I have a line on an NOS Y pipe for my 1970 300. The part number in my 1970-71 book is 3404 822, the NOS part I'm looking at is number 3583 980 and is specific for 440 engine after April 17, 1972. There is a third number for the same pipe before April 17, 1972. I know that part numbers changed for even the most minor detail, but since I'm building this stock I would like to make sure that the pipe will line up with the exhaust manifolds that I currently own, and hang correctly under the car.

Anyone know what happened on April 17, 1972 to cause a change in the Y pipe? Best guess would be some kind of smog change, but will it still fit my 1970?

Thanks in advance for any help.

 

[Samplingman]

Just wondering if anyone has any info to share or even a hunch. I'm guessing a Y pipe from '72 will fit, but you never know with MaMopar.

 

[70bigblockdodge]

I'm guessing 72 was the end of HP manifolds and the logs that carried through the formals showed up not that either flow better than headers. That statement should light the fuse on your thread.

 

[Samplingman]

Thanks, Dave. I'm actually running non-HP logs and single exhaust, I can't imagine there being much difference from the 1970 440 to the April 1972 440. As it is, the pipe looks like it runs down he right (correct) side for my 300 but I wanted to make sure before I buy it: