Rear end

[75gmck25]

It is possible that your truck has 4.56 gears, since it’s a one ton.

Changing from 16” to 17” rims is not the key measurement. You need to look at tire height, not rim size. In most cases a 33” tire will fit with no mods (originals tires were about 31”), and 35” will fit with only a 2” lift.

For a transmission, make sure you consider the transfer case adapter spline count. For example, if it was originally a TH400, it may not be a direct swap to a 700R4, but a 4L80 may be fine.

 

[idahovette]

Drivelines are gonna probably be longer/shorter???

 

[fnny6770]

Rear end in my 1980 GMC truck is a Dana 70, per the replies here so when I go to get gears or supplies for it do I just say a GMC Dana 70? Or do I now need to look at what size in inches the gears are?

 

[fnny6770]

It is possible that your truck has 4.56 gears, since it’s a one ton.

Changing from 16” to 17” rims is not the key measurement. You need to look at tire height, not rim size. In most cases a 33” tire will fit with no mods (originals tires were about 31”), and 35” will fit with only a 2” lift.

For a transmission, make sure you consider the transfer case adapter spline count. For example, if it was originally a TH400, it may not be a direct swap to a 700R4, but a 4L80 may be fine.

Now that I remember, you are correct in the transfer case adapter I'm pretty certain, when we put this standard transmission in we put the transfer case that was married up to in in the other truck but it came out of with it,

 

[bucket]

Now that I remember, you are correct in the transfer case adapter I'm pretty certain, when we put this standard transmission in we put the transfer case that was married up to in in the other truck but it came out of with it,

Get some pictures of the transmission, adapter and transfer case. We can then help determine what you have currently and what your options are for an overdrive swap.

 

[fnny6770]

Ok, thank you!