Front Diff ID

[OregonDMAX]

How to ID a front Diff with no sticker. I got a spare that has the sticker attached. Mine doesn't have the sticker, it's destroyed. How to tell what the gear ratio is? are there any identifying markings on the case or numbers?

Sticker below is of the spare diff out of an 06 2500 gasser

 

[2004LB7]

Give it a spin and count

 

[ZeroGravity58]

https://www.provenforce.com/Front Differentials/9_25_GMC_Front_Differential_.html

Look at the chart looks like it's a 4.10 I had this saved in my links

 

[2004LB7]

^^^ may be on to something. all the BZ6's are listed as 4.10

 

[TheBac]

Moved over to Axles/TC section.

 

[OregonDMAX]

Well that totally sucks ass, I'm pretty sure my truck is 3.73s as that's factory isn't it

Anyone know the RPO code off the top of their head for gear ratio for these trucks

 

[Chevy1925]

Yup, 3.73 are all we got.

Spin the pinion and count how many times it spins to make the driver side stub spin once

 

[OregonDMAX]

Yup, 3.73 are all we got.

Spin the pinion and count how many times it spins to make the driver side stub spin once

I was trying to take the easy way out and not have to split my case in half to fix the oil leak, o well

Spin the pinion trick never works right for me, I know I'm doing it right but it always comes out way off, hold one side spin the pinion and look at the other side, simple but not accurate imo

 

[Chevy1925]

I was trying to take the easy way out and not have to split my case in half to fix the oil leak, o well



Spin the pinion trick never works right for me, I know I'm doing it right but it always comes out way off, hold one side spin the pinion and look at the other side, simple but not accurate imo

Don’t do that. If you hold one aide, you have to count two turns on the free spinning drive axle side. Or just multiply the pinion count by two. The spider gears double the speed when you hold an open diff axle sold and the other spins.

If you let them both free spin, you get the right count.

 

[1FastBrick]

Well that totally sucks ass, I'm pretty sure my truck is 3.73s as that's factory isn't it

Anyone know the RPO code off the top of their head for gear ratio for these trucks

GT4=3.73
GT5=4.10
G80= Gov lock

 

[JoshH]

I've never seen a 2500HD truck with a 6.0 that didn't have 4.10 gears.

 

[OregonDMAX]

Don’t do that. If you hold one aide, you have to count two turns on the free spinning drive axle side. Or just multiply the pinion count by two. The spider gears double the speed when you hold an open diff axle sold and the other spins.

If you let them both free spin, you get the right count.

Spinning the pinion spins neither side unless I actuate the diff and I don't have it hooked to the truck. But it won't work anyway so it doesn't matter I guess haha

 

[OregonDMAX]

GT4=3.73
GT5=4.10
G80= Gov lock

Thanks!

 

[JoshH]

Spinning the pinion spins neither side unless I actuate the diff and I don't have it hooked to the truck. But it won't work anyway so it doesn't matter I guess haha

You can remove the actuator and have someone hold the plunger in to engage the locking collar while you spin it.

 

[OregonDMAX]

You can remove the actuator and have someone hold the plunger in to engage the locking collar while you spin it.

Yeah if I hadn't gotten the info I needed that's what I would have done, I'm just going to split my case and reseal it at this point. Just trying to save time by swapping the one I had laying around