I had a good video on my phone of the underside of the truck but I can't seem to find it and I'm not finding the information I'm looking for online.

What I plan to do is replace everything from the block back, in a mostly stock fashion. The previous owner let me know there was concern about clogged cats prior to him parking it for many years before giving it to me. In addition to that the muffler has rusted off and most of the piping is rusted to hell.

I'm still searching online for headers (or manifolds if I have to). I have the 50 series Delta flow (single in/single out) muffler that I want. What I need to know is: what is in the stock system as far as catalytic convertors are concerned.

I'm finding information saying there are 3 cats but I can't find pictures of a stock system for the truck. I've found some universal cats online but I'm looking more to get direct replacement style stuff and I've seen a few things but I don't know if what I'm looking at is right. I don't have the links right now but Summit is where I'm looking.

 

There will be several variations of stock exhaust systems on most years up to 1995 or so

That's just because of different State's Emissions requirements, by the mid-1990's the "Federal" standard was about equal to most states, although Calif. is still an issue, they require CARB approved Cats

My 1994 4.0l has 1 Cat

And prior to 1995 there is no O2 sensor after the Cat to test if its working, so on a 1991 I would just run one Cat Converter


Stock exhaust manifolds are Tuned for Mid-range power, 2,500 rpm range
Some prefer headers tuned to 1,500rpm range for better "off the line" power, but its users choice
Summit Racing sells headers for Ranger 4.0l

Unless a Header says "racing" its going to be for low end power, "racing headers" are for 3,500 RPMs

From the exhaust manifolds/headers back its mostly all the same, 2.25" tubing on all single exhaust Rangers up thru 2011
Rangers did come with dual exhaust, would be quite a bit more money, basically doubling up on every thing, pipes, Cats, Mufflers

 

I thought, from what I've been reading, it was 2". Either way I'll get it figured out in a couple weekends when I get to go messing with it again.

Now I see why I am seeing so many variations reading stuff on the interwebs. Basically I just got to get under there really well and look then decide.