Catalytic converter

[xboxrox]

If the upper converter is plugged, does it necessarily follow that the lower one is plugged too? (Others in the community may be able to answer this question.) If only the upper cat may be plugged, why not remove it, give it your proposed treatment, then see if the problems persists? If so, then get the lower cat and install it. Dividing the repair into two parts would require little duplicate effort, but also save purchasing the lower cat if found replacement isn't needed.

Also, I have MD100652 as the P/N for the lower cat. A few Mitsubishi parts warehouses list it (but that doesn't mean they actually have it) for around $350 plus shipping. The P/Ns for the upper cat are MD084434 / MD167726. Lists for $275.

TODAY'S PROGRESS

FMS thanks for this info ~ it was too late to phone mainland Mitsubishi dealers today by the time I got finished with other phone calls to O'Reilly's, Carquest, E-Trailer, Magnaflow Co. etc...( must check availability of these Mitsubishi Part #s you provided...)

Phoncon Results today:

O'Reilly's has Magnaflow 334104 CARB cat $229.00 + $10.00 shipping
Magnaflow Co. says their direct fit FED cat MAG23238 is no longer available (rep said their CARB & FED cats are same..!?!)
Walker website states that a CARB cat should last longer than FED with it's better outer coatings & better (more?) chemicals inside
CarQuest has Walker FED cat 15051 $121.99 Free Shipping
MPC MB687020 Gasket exh manf to exh piping is available (no answer yet on rear gasket...) OEM cats obsolete & not in stock nationwide
MEGAZIP website shows part #s for the bolts springs etc to connect piping to exh manifold (not checked yet)
Pacesetter direct fit FED cat listed as no longer available at Summit Racing and other sites as well; will phone PaceSetter Co.
E-Trailer says Magnaflow Direct Fit FED cat MAG23238 is no longer available

Looks like cutting & welding the SS409 piping of a new cat will be required to install either the O'Reilly's CARB cat or the CarQuest FED cat ~ IF the original piping on my truck can be reused after removing the old cat... IF so, then maybe mgr Chad at Five-O-Motors will allow me to work with his one employee that knows a little about welding ~ providing their weld machine & equipment is operational & capable of using the proper welding wire for SS409 exhaust piping BLAH BLAH ah HECK..!?!
To conserve energy and time & most likely have a sat fix; will measure the O.D. of my truck's exh pipe then order the rear cat and hope all goes well removing all the bad & installing a new rear cat (exh manf will not have a cat unless MD167726 is available; will phone MPC again...)

QUESTIONS

Has anyone ever removed the upper catalytic converter case from the exhaust manifold..? Any help with this is much appreciated & does anyone know if the exhaust manifold with rear cat attached can be removed from the truck in one big piece..?

My engine is still using plenty oil even after installing a new cylinder head ~ oil ruins catalytic converters ~ maybe there is a way to help piston rings seal (soak Marvel Mystery Oil into the cylinders..?) The cylinder head & oil pan need removal to access rings, right (?) Wow a rebuilt short block in my future..? Shipping to Hawaii..!?! The CARB cats are built to last 5 years or 50,000 miles while the EPA & FED cats for 25,000 miles... RockAuto has a 1986 MM DEC brand CARB cat for $1,679.00! Will phone DEC see if they are still in business, prices and if they might sell me the parts only for DIY welding...

Phoned Jeff @ DEC and he referred me to ebay store BIG RED AUTO PARTS (a Calif dealer that sells DEC products) contacted Big Red through their ebay store & their Facebook page; they acknowledged receipt of my mssg and will get back to me soon...