General Tech The Dana 70 Bible

[CactusDave]

I’ve got a 3500 Chevy express with a Dana Super 70. Im wanting to put an e locker in and I’m finding conflicting information as to whether the super 70’s even come with a 3.73 gear ratio or if they’re only 4.10 or 4.56.
The reason being is because I’m trying to determine if I have to regear the diff and/or replace the axel rods in order to get a locker that will correspond to the 37 splines as every option seems to be 35.

 

[Greg]

I’ve got a 3500 Chevy express with a Dana Super 70. Im wanting to put an e locker in and I’m finding conflicting information as to whether the super 70’s even come with a 3.73 gear ratio or if they’re only 4.10 or 4.56.
The reason being is because I’m trying to determine if I have to regear the diff and/or replace the axel rods in order to get a locker that will correspond to the 37 splines as every option seems to be 35.

Selectable locker options for the Dana 70 aren't great to begin with, but I'd assume 35 spline is going to be the only option.

Is there a diff tag on your axle indicating your current gear ratio?

 

[CactusDave]

Selectable locker options for the Dana 70 aren't great to begin with, but I'd assume 35 spline is going to be the only option.

Is there a diff tag on your axle indicating your current gear ratio?

No diff tag, unfortunately. My mechanic said he called in the VIN to GM dealer and he said they told him it’s a super 70 which means it’s a 37 spline and that it has a 3.73 gear ratio. What’s odd is I can’t find any info online that says super 70’s have that gear. Everything indicates either 4.10 or 4.56. My original thinking was that if I regear it from 3.73 to 4.10 then I could find a corresponding locker but now it seems I’d have to have the axel rods swapped too.
Is the only option to remove the diff cover to investigate what rack and pinion I have?