I'm looking at a 1991 F350 ex-cab dually 7.3/E4OD 2wd for a tow rig. I'm stumped by the "D5N" axle code. I've never seen a 3 digit axle code on a Ford before. I know the "D5" means a 4:10 limited slip but does the "N" denote a dually rear?
Thanks.

 

iv seen this come up for the 8th gen trucks before.im not sure it's known what the N means.iv speculated it denoted Non limited slip,but yours is most interesting as it's clearly the LS axle with the letter in the code (your "D")
iv not seen someone post they have an N in the code that's also a LS axle.

 

the 3rd Character may designate a factory front limited slip differential, which is rare, but were still produced.

 

but why would a 2 wheel drive have a "factory front limited slip differential"??

there is no listings for a 3 digit axle code in the service manual.

 

I wish I took a pic of the manufacturer sticker. The guy decided not to sell the truck. But it's had me curious what the code was. I've looked at a lot of axle codes in the local pick a part and I've never seen a three digit code before. After doing some reading I'm thinking the D5N is the code for a 4:10 limited slip DRW Dana 80. From what I read, Ford used the Dana 80 in the following:

• 1988-1998 F-350 DRW (Select chassis cabs and pick ups)
• 1999-2011 F-350 DRW
• 1988-2004 F-450
• 2011-2012 F-450 (13,050 GVW)

 

I didn't see that

 

the dana 80 (of the idi and fist gen psd era) was only placed in the '87-97 F-super duty (F-450) trucks and the gear ratio options were limited to just two,and without LS option (sadly,especially since they were all only 2wd too)
axle code 72 - 4.63
axle code 73 - 5.13

the f250/350 (srw or drw) pickup and cab and chassis got the sterling 10.25 with the 3.55 or 4.10 options w/ LS or open.

but.......who knows.you found a weird 3 digit code truck too.to bad you didn't inspect the rear axle to see if it was in fact just a sterling (in '91 it would be the first gen with shorter yoke.)

 

I'll try and e-mail the guy and see if he'll send me a pic of the manufacturer's sticker and one of the actual diff.

The info I got on the D80 being in some F350's was from the Wikipedia page on the Dana 80.

I looked at the diff when I was checking out the frame of the truck but didn't think to pay attention to it. I did see the tag was still attached but with the harsh Winter's we get, I'm not sure it would be readable. At the time I just figured it was a regular 10.25 and the N likely meant dually. My 89 is the first F250 I've had so I'm use to the 8.8 in the F150's and Bronco's.

One thing the seller mentioned was it revved high. Like 2000rpm's while doing 80km/50mph with the E4OD. He traded for it as a project so he hasn't driven it much but did say it took off better than anything he's driven truck wise. It has an older Banks turbo kit so the gears might have been changed as well. I have a buddy who works at the local Ford dealer so I'll see if he can ask the mechanics about the code.

 

I did some more research tonight and found more info that suggests some lucky F350's did in fact get the 35 spline D80. There's an article from Four Wheeler Magazine about the D80.

Exploring The Beefy Dana 80 Axle - Four Wheeler Magazine

From the FWM article:

"The super-tough Dana 80 rear axle ranks as one of the most desirable axles for off-highway use. It's a full-float unit with 11.25-inch ring gear diameter; 1.625-inch (minimum diameter) 37-spline pinion shaft; 11/2-inch-diameter, 35-spline axleshafts; and a 4-inch axletube diameter. It has an 11,000-pound gross axle weight rating and a continuous manufacturer's output torque rating of 2,500 lb-ft. As a bonus, there are quite a few Dana 80 axles available due to the fact they were used in a variety of mainstream applications over the years, including some '94-'02 Dodge 3/4- and 1-ton trucks and '88-and-later Ford F-350 and F-450 Super Duty dualie trucks."

I also found threads on the Pirate 4x4 website where a guy talks about seeing an F350 with the D80 instead of the 10.25. Apparently, if you order certain options you could wind up with a D80.

"gbkeith" on pirate 4x4 said:

"F-superduties got 37 spline dana 80's. Some 350's got 35 spline dana 80's. The only reason I ever noticed was because I happened to glance down at one without a bed and noticed it wasn't a sterling. No idea if it was a 1 in 10 sort of thing or a 1 in 1000. I don't have a picture, but here, Exploring The Beefy Dana 80 Axle - Four Wheeler Magazine"

and . . .

"From 88 to 98 some chassis cab F350 drw's and pick ups got 35 spline dana 80's. The only super duty duallies that had a sterling instead of a dana 80 were some that came with 5.4 liter engines.

I don't make it a habit to look under every OBS duallie I see, so I could be full of **** on this next part, but I think camper package, engine size, and luck of the draw determined who got an 80 and who got a sterling."

 

Good news. I just got another chance to buy the 1991 F350 dually with the D5N axle code so were going to get an answer. I have to wait until tomorrow to pick it up. When I get it home I'll take pics of the manufacturer's sticker with the D5N code and pics of the diff itself.

 

Here's a pic of the D5N axle code and the diff itself. To me, it looks like a 10.25 Sterling and not a D80 but I'm a newbie to these rearends so I could be mistaken. But I have never seen a three digit axle code on any truck. I've owned at least 12 87-96 F-series trucks and looked a hundreds in the local pick a part and never saw a code like this. I checked the Ford manual and none of them list a D5N code either.

 

here is another.same as yours.a 2wd truck.thread dead ends.
https://www.ford-trucks.com/forums/1...axle-code.html

i see "FT" (ford truck) in your vin.it's a 2wd pickup not a cab n chassis like it would be if it was "FD" (ford incomplete vehicle.) as well a 3" wide rear leafs.
so it doesn't stand for "Narrow" rear axle.it's the wide pickup drw axle.iv no idea brother.
it's not a D80.the D80 in my log truck has a fill plug right in the cover.............and since this thread began,iv still not heard of a dana 80 rear axle placed under anything other than the f-super duty/f-450 pre-super duty era either.

the "tape" appears blank.perhaps the "N" truly belongs under "tape"? what is that anyway? pin striping or other graphic code? if so,then perhaps it wouldn't have a tape code anyway if it's a base model/solid color.

probably a typo.that's my best guess.

 

The only thing I was thinking was that my truck has chrome rims and end plates for the axle shaft end plates. The thread you mentioned shows a dually with chrome rims in his sig. Maybe the N denoted a chrome appearance package??? But I don't think it would be reflected in the axle code. Here's some more pics of the truck and front of the rear diff.

 

It's a 1991 F350 Supercab. It has buckets, power windows, and the cloth inserts on the door panels so I don't know what trim level it was. The truck appears to have been white originally so I don't know about tape graphics.

 

I have a C5N axle code on my 1991 F250 and since buying it could never figure out what the N really meant. No dealer, tech, or independent shop I've asked - and spent money with, not just nagged - could tell me what it means.