Got this with the truck when I bought it. Can't figure out what manufacture it is. It's a 4-1 if that helps. O2 sensor bung is on the 3-4 primaries as well. haven't measured the primaries either yet. Looks as though its a 2.5 collector. possibly a 2.25 however it seems larger than my 2.25 exhaust thats on it.

 

I figured I'd save you a jab, so here ya go.....

This is his header, I just happened to take the picture.

 

lol ooops i knew i forgot to put up that photo hahaha thanks again

 

I think I found it, however the flange on the top is a little different and has a dip between #1 & #2 then again between #3 & #4
Downey header but the guy had it on a 20R?????




Close primary bends are close but look at the flange difference

Another Downey header


not this one:

HI-TECH ULTRA TORQUE
TRI-Y HEADERS




Not this one:
Hedman Elite Ultra Duty Header


Not this one:
Pacesetter


Not this one:
LCE Street Header


Not this one:
LCE PRO Header


Definitely not this one:
Doug Thorley Header

 

seems you have a downey, looks the closest....

 

that's what I am thinking, it was pretty rusted too on the bottom, maybe they changed the flange part way through the production process. Who know hows old it is.