Replace the mid pipe with a straight piece of 4" pipe...then there is no offset.

Or rotate the mid pipe till it works...either way is sufficent.

 

Check out the price of that muffler at this place: http://www.a1truckparts.com/exhaust.html

Anyone find a better price than $47.60? Seems like the econo-route to a better sounding truck when mine gets here.

 

Cummins N.W. is now Cummins Rocky Mountain...looks like they had a pretty good price increase. The 86131M is now $103.33, so much for $66.00.

 

Heres a question, im going to order the nelson 51" and have someone install it. i talked to meinekee (SP?) and they said they could do it with an hourly charge... i doubt they know about the offset that they have to deal with... if i take my truck any where to get it installed will they most likley know what to do with the offset or is it something they will screw around with untill they start adding crap under there that i dont need and hand me a 300$ bill... thanks

 

Just watch them...all they should do is cut off the OEM muffler, slide the rear of the new muffler over the tail pipe, slide a 3.5 to 4" adapter over the front of the muffler, and then either trim the existing mid pipe to fit...or have to use a short piece of straight 3.5" mid pipe and it will all line up. Make sure they cut off the oem hangers from the oem muffler and reweld them onto your new muffler for support.

 

just ran out and bought a 51 in. donaldson,,went straight to the muffler shop,,,the guy said he couldn"t do it cause of the offset!,,i have a 04.5 with 4 in. exaust,,,it"s a short bed,,there is not a whole lot of room for a 51 in. muffler,,do u guys all have long beds?,,if i do find someone to put it on,,is it going to mount at least half way straight? or is it going to be crooked and ugly?

 

The mid pipe (just ahead of the muffler) has the offset in it. If you replace cat back or just ahead of cat (if it happens to fall off) to the new muffler with a straight pipe of 4" pipe...it will line up.

In other words...see if your tail lpipe right behind the muffle lines up with the pipe right infornt of the cat...it should work.

 

i have a 04.5 short bed,,,,,just bought a 51. donaldson today,,i think what u guys have been discribing installation doesn"t apply to a 04.5,,i think this because i have a cat. on my mid pipe just before the stock muffler and there just doesn"t seem to be enough room between the cat and where the exhaust pipe starts going over the rear axle for a 51 in. muffler, also,,,i don"t think the existing hangers will be of any use,,,,,,can anyone help me out,,has anyone worked thru this problem? ,,i don"t want to destroy the exaust system and have to replace it,,,,,,,,,,,,,,,thanks in advance,,,,,,,,,,,,,,,,,,ed

 

keep asking different muffler shops, they can do it they just didnt wanna go through the trouble, you will find someone to do it, even places like meinekee (SP?) car-x, auto zone etc... can make it fit

 

yup, you're just talking to lazy exhaust guys... don't press them or try to get them to do the work cuz if they do, they'll half-*** it...

it's a pretty dang simple install...

Forrest

 

Ditto on that. If an offset is kicking their ***, they wanted their *** kicked so they wouldn't have to actually bend a pipe. I've worked at a muffler shop before, and that is no reason to turn down a job. Anybody that knows what they're doing can cut a section of pipe out, and replace it with a piece bent to take up the offset.

 

All Freightliner dealers handle them. Usually they have a very good price also.

 

I used the 26" Donaldson. Sweet fit,..no fab problem at all.

 

Does any one run the M085171 40" Donaldson muffler, here are the comparsions!!!


M090544

Exhaust Mufflers Product Attributes
A - Inlet Diameter (Inches): 4
B - Body Diameter (Inches): 9
D - Overall Length (Inches): 51
E - Outlet Diameter (Inches): 4
Rated Flow LR (CFM): 1158
Rated Flow MR (CFM): 1638
Rated Flow HR (CFM): 2006
Back Press LR (In Hg): 1
Back Press MR (In Hg): 2
Back Press HR (In Hg): 3
Attenuation (dBA): 13-18
Product Type Description: Muffler, Round, Style 1
Primary Application: OFF ROAD APPLICATIONS

M085171

Exhaust Mufflers Product Attributes
A - Inlet Diameter (Inches): 4
B - Body Diameter (Inches): 8.5
D - Overall Length (Inches): 40
E - Outlet Diameter (Inches): 4
Rated Flow LR (CFM): 1800
Rated Flow MR (CFM): 2546
Rated Flow HR (CFM): 3119
Back Press LR (In Hg): 1
Back Press MR (In Hg): 2
Back Press HR (In Hg): 3
Attenuation (dBA): 8-12
Product Type Description: Muffler, Round, Style 1
Primary Application: OFF ROAD APPLICATIONS

 

Perfect timing! I just today was doing some research and decided I am going to go with the Donaldson 40". I want it fairly loud, but not annoyingly so. I hope it fits the bill. I will try to mount it as far forward as possible, so hopefully that will cut down on any drone. Oh and by the way, my local freightliner dealer didn't have them in stock, as they only stock 5" mufflers.