localnet

Hi All!

I bought the front and rear diff covers from Diesel Performance Parts, installed the front one, fit perfect. Checked out the rear, no fitty. Turns out I received the proper diff cover for the 2500, but that is not what I have under the truck. Its a 3500 rear end! I'm not complaining, just wonder how common this is? Anyone else have this set up? Does this make my 2500 a mislabeled 3500?

The 2500 cover is flat on the top and bottom. The 3500 comes to a point on the top and bottom and is of course bigger in circumference. I checked the 3500's at my dealer, same axle that I have on my 2500. Go figure?

Just thought I would let you guys know. Might save you all some headaches down the road.

Mike

FastZilla

There is a 10.5" and a 11.5" rear end that you could get behind the diesel. My `05 2500 has the 11.5". The specs, year ranges, etc. I don't know. Do know that the 11.5" is the biggest SRW axle they got.

Oops, you got an `03, dunno You might of got one in the Dana to AAM transition... All speculation....

localnet

I don't know either? It is an 11.5 according to the glove box tag, maybe I should ask the dealer? Not really concerned, but I thought the different axle sizes refered to the front only, 10.5 or 9.5? I looked under a couple of new 2500's, they had a different rear axle then mine (the diff cover I have would fit those 2500's, but not mine). The 2 3500's, one was a dually, had the same "looking" axle as mine. Just found it interesting, anyone else have any ideas?

Mike

tony

Every 2500 '03 auto I've seen has the 10.5", while all the 2500 '04s I've seen had a 11.5".

ih1586

03 2500 SO has the 10.5",03 2500 HO has the 11.5".

bulabula

First time I've ever heard of the AAM's described as a 2500 model or 3500 model. Wonder if they're called that on GM's?

I've had an 11.5" AAM on mine for over two years now.

In '03 I think it went like this:

- All HO equipped trucks had the 11.5"
- All 3500's had the 11.5"
- All manual tranny equipped trucks had the 11.5" (2500's and 3500's; 5 spds and 6 shooters)

- Only automatic (47RE) SO 2500's had the 10.5".

No matter, either one is plenty hefty for the job at hand. Heck, I think my front 9.25" diff is bigger than the rear diff on the Mighty Nissan Titan - and wll all know that truck is a pulling god......

1sttruck

My truck is like bulabula described; it's a 5 spd SO and has the 11.5in axle.

bhoeffner

Mine is a 04 purchased in Nov. of 03. I have the 11.5 AAM. I thought that in the early 04's you could have ether a 10.5 or 11.5. If I remember right the dealer said it was due to a towing package on the truck? Not sure if that is correct or not. Sound to me like you need to send that one back and get the cover for the 11.5 AAM.

localnet

Thanks for all of the info guys!

I received the right cover after calling DPP. They were very quick to send out the correct one with a return box. Had it in 2 days, good guys to work with.

Learn something new everyday!

Mike

FastZilla

Nope. The 10.5"er is refered to as the GM 14 bolt. That was my rear axle in my trail rig - I always knew I'd get home with the rears spinnin'... The 11.5" falls into the "OMG" catagory - I'd like to see the the beast of an engine that can snap one of those axles... We really don't have much more to go until we get into the Rockwell axle ranges/strengths.... Yummy....

localnet

It is nice having these monster axles on our trucks! Just looking at the internals of the front were reminisent of my semi, can't imagine snapping anything in there. With proper care, who knows how long these axles will last.

Mike

mjf6175

If you have a diesel in a 2003/04 you get the 11.5 axle whether it is 2500 0r 3500, its part of the diesel package and why the option costs as much as it does. Its a 10.5 rear if you have a gasser.

Jonesey

Wrong! See the above post by bulabula. He is right on the money.

Pointing Labs

I have the 11.5, now I have a question, I had the pinion factor changed because of the tire size 295/70/17 and had them plug in 10.5 for rear axle when it is 11.5....how bad will this throw me off and should I go back and have it changed again?

Jonesey

The ring gear diameter should make no difference. The determining factors would be the gear ratio and the tire's revolutions per mile. The tire manufacturers normally list the revolutions per mile on their spec sheets.