Best diff ratio and how to find out what ratio is in it?

[V.W.Dave]

At work we are just about to rebuild a 1998 GU Patrol from factory it was a 2.8 5 speed Ti nothing fancy about it. How do I find out what the diff ratios are without taking them apart? I know I have read somewhere that there is something on the compliance plate or something. I know you can lift the car up and spin the drive shaft and count the wheel revolutions but I need to be 100% sure on this and don't want to just eye ball it and guess. From my very limited knowledge of Patrols they came out with 3.9, 4.11, 4.3 and 4.6 in the GUs and most of the TDIs had 4.3 or 4.6 and "most" of the 2.8s had 4.6 ratios. other then that I am clueless.

Second Question
We are replacing the 2.8 with a rebuilt 4.2TD and trans. The transfer will have gears but the High is still 1:1. It will be running 35" tires. What is the best ratio to be using? I have read that the 4.3s are best for drivability but the 4.6s make the speedo almost perfect.

Please help me Nissan gods

Thanks

[supazuk]

Look at the diff code on the compliance plate.

[tas80]

bottom right corner of the compliance plate where it lists trans/axle codes.

HG46 is a 4.6 ratio and is what I'd expect the 2.8 to have.

The two numbers in the axle code refer to the diff ratio.

[GUtripper]

Unless you are doing lots of towing and the engine will be stock (ie no boost, retune, exhaust etc) you may find the 4.625 ratio diffs are a bit short, esp if lots of highway work is planned. Revs will be more than 2500 at 100kmh.
4.3s will be better, but given the cost of swapping it may not be worth it.

[V.W.Dave]

bottom right corner of the compliance plate where it lists trans/axle codes.
HG46 is a 4.6 ratio and is what I'd expect the 2.8 to have.
The two numbers in the axle code refer to the diff ratio.

Thanks mate thats what I thought. The patrol dosnt get here till Thursday I just wanted to know what to look for when it gets here

Unless you are doing lots of towing and the engine will be stock (ie no boost, retune, exhaust etc) you may find the 4.625 ratio diffs are a bit short, esp if lots of highway work is planned. Revs will be more than 2500 at 100kmh.
4.3s will be better, but given the cost of swapping it may not be worth it.

The 4.2 has been completely rebuilt. It has bigger injectors, a higher output pump and will be getting a bigger garret turbo, a water to air intercooler all dyno tuned.
This guy is building this thing to take a 3 year trip around australia he dosen't care about the cost of changing ratios he just wants to make sure its the best for what he is doing. It will be towing a fold out camper trailer but not all the time. We are putting lockers in it next week and wants to make sure of the ratio when we are doing them. SO if its a 4.6 and he needs 4.3s then we will replace them then.

[turbo gu]

4.3s. are the best choice. I have had both 4.6 and 4.3s in my GU. would only run 4.6s if I was going to 37s.

[RED60]

VWD... don't forget that what is on the ID plate MAY NOT be what's in the thirds.... it indicates what the vehicle came with, what if they've been swapped already?

[GUtripper]

VWD... don't forget that what is on the ID plate MAY NOT be what's in the thirds.... it indicates what the vehicle came with, what if they've been swapped already?

Yeah true, but no one would swap taller gears into a 2.8, it would never pull it. Or, blow up lol

[V.W.Dave]

VWD... don't forget that what is on the ID plate MAY NOT be what's in the thirds.... it indicates what the vehicle came with, what if they've been swapped already?

Yeah true, but no one would swap taller gears into a 2.8, it would never pull it. Or, blow up lol

The GU was owned by a family and was used as a shopping trolly. So it should be as is from factory. (fingers crossed)

Next question. (I am a toyota/Suzuki guy and have never messed with Nissan stuff till now)
Is there a solid spacer option for the patrol diffs? If so is it worth the hassle?

[Flexen-Gu]

What do you mean by solid spacer? As in crush tube for pinion?

Patrols run a solid spacer if that is what your referring to.

In my ZD30, i added 35's and 4.6 diff gears and that brought the speedo to being back to spot on.

all 2.8's i have ever seen has had 4.6 diff gears