What factory gear? '76 D-100, factory 4x4, 400ci big block, auto

[brad54]

I could go out, crack open the dif and count teeth, but does anyone have an idea of what the factory gear ratio would be in this truck?

'76 D-100 4x4
Full-time four wheel drive
400ci engine
727 auto trans.
The speedo reads accurately with the 31-inch tall tires, so I'm thinking it's all just like it left the factory.

No tach, so I can't figure out the ratio.

Thanks,
-Brad

 

[bear]

More then likely 3:55's . I take it there's no tag on either one of the covers ? What you could do is jack it up , mark your tire , mark your drive shaft and then spin your tire one revolution while counting how many times your drive shaft turns . If you have 3:55'a then your drive shaft will turn about three and a half times .