I have an 04 F150 SCAB 4x4. I am wanting to put the Magnaflow Cat Cack exhaust on but it states that it fits 04 5.4L June 01 and later mfg dates. Where can I find this info on my truck. On the inside of the door it says 01-2004. Is this the correct MFG date?

 

That is correct. Your build date is Jan. 04. If you want a Magnaflow cat-back, you need to know that there was different part #'s for 04 specific F-150's (build date pre June 04)
They are,
#15821 is a SI/SO
#15834 is a SI/DO rear exit
#15827 is a SI/DO side exit (lightning style)

 

Thanks for the info! Is there anything bad to having this early MFG model? Were there any specific things changed after June that I should know about?

 

I'm not positive, but it was my understanding that the location of the connection between the Y pipe and mid-pipe was moved starting with June 04 and later built trucks. That connection is right where the cat-back ties into the stock exhaust, hence the need for two different systems.

 

Thanks again for the info!