Differential Question

[grose67]

I have a 98 GMC Sierra. The RPO Code shows I have 373 gears. Isthere a way to know if this is a limited slip unit or posi unit ? It acts like a one wheel wonder but I have noticed that at different times, different wheels are spinning.

[59ih340]

I think it would have a G80 RPO code also.

[Nytemare]

I have a 98 GMC Sierra. The RPO Code shows I have 373 gears. Isthere a way to know if this is a limited slip unit or posi unit ? It acts like a one wheel wonder but I have noticed that at different times, different wheels are spinning.

RPO code G80 for a locker.

 

The other way to tell is jack it up on one side and try to spin the tire by hand. if you can keep spinning it its an open dif. if not Its got an LSD or locker.

 

Just look at all your RPO codes in the glove locker and compare them to the online list. Someone posted it on here a couple days ago. This is the easiest way....or go into the dealership and and give them your VIN and ask what options it came with.

[grose67]

Where would the other RPO Code be located?

[Nytemare]

Where would the other RPO Code be located?

They're all in the glove locker... On a sticker. There will be a load of them.

[gmtech4]

holy crap nytemare,I'll beam you up and then you beam me up ok?

[Nytemare]

holy crap nytemare,I'll beam you up and then you beam me up ok?

WTF rob...you drinkin again????

[dlstewart01]

You will have either an open diff or a G80 Eaton locking diff. Look for RPO code G80 in the glove box.

 

The GM trucks could be had with a G80 locking differential with the exception of the Quadrasteer which could be equipped with a G86 limited slip. GM cars with a G80 were limited slips.

 

The Eaton G80 locker will lock the rear wheels together when one rear wheel spins 100 RPM faster than the other. They will unlock when a speed of 20 MPH is reached. This was designed to get you unstuck at low speeds. They were not designed for racing and will some times explode under those severe conditions.

 

If you jack up the rear of the truck and spin one wheel by hand, the wheels will spin in opposite directions with an open diff. A limited slip would spin the wheels in the same directions.

 

An Eaton G80 locker will also spin the rear wheels in opposite directions because it will be an open diff when not locked. Some times you can jerk one wheel enough to engage the locking mechanism and the wheels will then spin in the same direction.

 

If you turn the drive shaft to turn the wheels the rear wheels will both spin on the same direction no matter what diff you have, whether it be open, locker or limited slip.

[grose67]

Here are the RPO Codes I found:

YD3 Differential, driver-selectable locking rear driver selectable?

YD3 Differential, driver selectable rear locker

YD3 Front Axle For Scheduling GVW Plate Dont know what this is

YD3 AXLE (BASE EQUIP) FOR SCHEDULING GVW PLATE Dont know what this is

[dlstewart01]

Here are the RPO Codes I found:

YD3 Differential, driver-selectable locking rear driver selectable?

YD3 Differential, driver selectable rear locker

YD3 Front Axle For Scheduling GVW Plate Dont know what this is

YD3 AXLE (BASE EQUIP) FOR SCHEDULING GVW PLATE Dont know what this is

 

 

In your case YD3 is for front axel base equipment. You do not have a locking differtial if you do not have RPO code G80.