1991 Suburban V2500 Question?

[Deercreekfarm]

I have my 1991 Suburban V2500 with a 14 bolt semi float (9.5”) rear axle. I found a 14 bolt full float (10.5”) rear axle out of a 1995 Suburban K2500.

I know aside from making sure the gear ratios are the same is this a direct bolt in swap? Or are there other issues with using a newer axle in an older vehicle.

Thanks,

[zieg85]

spring perches will not be the same.  I would think you could find the correct FF for your application?

[Deercreekfarm]

Okay thanks for the info. As I was looking into the gear ratio here is what I came up with:

Rear axle: 3/4 ton semi float
Gear Ratio is 3:45




Front axle corporate 10 bolt
Gear ratio ?
I would assume it’s the same as the rear but the rear differential says GM3 and the front differential says GM6 can anybody help me figure this out. All the axle codes I find on line are for the rear axles.

[zieg85]

Best to look in the glove box at those 3 digit codes.  Focus on any of the G-- and H--

[Deercreekfarm]

So the only two “G”’s in the Glove box is GT5 which I looked up and is 4:10 gear ratio and a G80 which appears to be limited slip. So obviously that doesn’t match either of the stamped differentials. I’m wondering if a previous owner swapped axles or I’m missing something?

[zieg85]

So the only two “G”’s in the Glove box is GT5 which I looked up and is 4:10 gear ratio and a G80 which appears to be limited slip. So obviously that doesn’t match either of the stamped differentials. I’m wondering if a previous owner swapped axles or I’m missing something?

The only true way is to take off the cover and see what is in there.  The gear is stamped and you will know for sure.  4.10 is an easy ratio to match in a FF.  3.42 where only in the SF.

[csdineley]

Not true. 3.42 were available in 14b ff. Just really hard to find. I just swapped out one on mine.

[Deercreekfarm]

Not true. 3.42 were available in 14b ff. Just really hard to find. I just swapped out one on mine.

Yeah I’m on the hunt right now for a pair of  3/4 ton FF or 1 ton axles to put under it.

[zieg85]

Not true. 3.42 were available in 14b ff. Just really hard to find. I just swapped out one on mine.

Interesting.  All the info I have doesn't mention the 3.42 in a FF factory set up just aftermarket.  Thanks for the correction

[csdineley]

No problem, With an sm465 I thought it was a pretty good combo. Took a long time to find one with 3.42 gears. But it came out of an late 80's Suburban 2500 with a 6.2 and th400. Seemed like a cheaper option then swapping to an Nv4500. Interstate driving 70 mph @ 2600 rpm and on flat land I could avg 16 mpg if I stayed around 55 mph.

[Irish_Alley]

that sounds like a good rear end for my cummins, only issue is the dana 60