First time owner! Rear axle ratio swap?

[Tatohead]

Hello!

Loving this truck! According to my tag in the door jam, my 68 D100 axle is a 3.55

I would prefer something more highway friendly. Reading on this site, it would seem that 3.23 is an option. This being a 3rd member type axle, can I just perform a simple swap with the same housing and axle shafts?

Truck has NP435 and non-original 273 LA.

THANKS

[Jim100]

Pretty sure direct swap but man the 3.55 is a good ratio. You should verify what ratio you have as it may not be what is on door and check to see if a limited slip is in there as you don't want to lose that in a swap. (I made that 400 dollar plus mistake )

[Hobcobble]

Hello!

Loving this truck! According to my tag in the door jam, my 68 D100 axle is a 3.55

I would prefer something more highway friendly. Reading on this site, it would seem that 3.23 is an option. This being a 3rd member type axle, can I just perform a simple swap with the same housing and axle shafts?

Truck has NP435 and non-original 273 LA.

THANKS

I'd look for a 742 or 741 case gear set in either 3.23 or 2.94.
If your 3.55 is a Sure-Grip.... don't get rid of it....

John

[Tatohead]

I really appreciate the replies! I'm hoping I can hit 65 mph at something like 2700 RPMs or under. Perhaps a slightly larger rear tire will be a part of this goal.

[Tatohead]

Just for fun, the door tag

[Kaegi]

with a 30 inch tire, 3.55 gears, you will be going over 67 MPH at 2700 rpms.

[Tatohead]

Good info. 65 is target speed, so I am just fine keeping it as is. Thanks!