How can I ID my rear diff without using year, model, or VIN?
Reason I ask......
My truck is a parts truck and I have no idea which diff's I have and have no idea how to identify.
My truck is titled as a 2004 1500 4X4 gasser and this matches the vin on the cab.
The VIN on the driver door says it is a 2004 3500 4X4 5.9.
My truck has the 5.9 HO CR
47RE
4X4
8 lug (single wheel)
Exhaust at the turbo is 4 inch
I know the cab and trans do not match the door, but who knows what else...
The story ----
I have developed a vibration while driving.
No play in drive shaft, but have not removed.
Set rear wheels on stands and still get vibration (starts around 40'ish mph or so).
Vibration goes away on deceleration on the road and on stands.
Removed rear cover of diff, no metal debris.
Removed rear wheel bearings - both sides are good.
U-joints will be replaced when they get here, but I do not know which lube to get for the diff as I have no idea what it is (Gen 2, Gen 3, other?).

Thanks much,
KC

 

The OEM rear axle for that truck would be an AAM 11.5. Assuming they are indeed 3rd gen axles, the 4" axle tubes would be the quickest way to differentiate it from a 10.5 that was in 03 SO trucks and SRW gassers of that era. If there is a chance someone swapped in 2nd gen axles, the rear would be a D70 or 80 which look completely different. A 2nd gen SRW gasser had a D60 rear.

 

I measured the axle tubes and looks like 4 inch it is.
So.... Gen 3?