Identifying if GU patrol 5th gear has been replaced

Hi Guys
I'm getting more and more worried about towing in 5th gear after reading and hearing about the weak splines in the early GU boxes. I have a mid 2000 tb45 patrol and have towed my loaded 4m tinnie around the state to a few dams and have dropped it into 5th on the odd occasion and its always in the back of my mind but my greatest concern is the possibility of building a work trailer which will be quite heavy considering my occupation and I don't want to drive the highway in 4th if i can help it.
Now what I'm wondering is, can you tell if the 5th gear has been replaced by either looking internally (through the top) or via Nissan. Do they keep recall / warranty rebuild records via VIN.
The patrol also came with an electric brake controller fitted so that tells me that the old guy that owned it before me towed a van by the sound of it and from a little reading around here, a brake controller could be an indication that the box has been modified but can also mean that 5th gear could be closer to spinning from prolonged towing.
Now please don't tell me that I should just tow in 4th etc etc, thats not what im asking. I simply would like to know if there's a way to see if its been done or not.
Cheers

You can but will most likely have to pull 5th gear out to do so.

They tend to send the gearbox oil a orange/rusty when 5th is on its way out. If it does let go for the most part it doesnt effect the working of the rest of the box so you can continue to drive until you source another box or have yours repaired.

Imo even with the weaker gear towing in 5th is fine for the easy stuff..
Nice flat ground etc.
Once in the hills it's best to drop it back regaurdless of the weak 5th or not.

I've only ever towed in 5th gear downhill then drop back to 4th once it starts to labour again on the flat - never ever lug in 5th . Everyone has different trains of thought on this so its up to you mate . I used to tow a 9x5 tandem trailer with a 1000lt diesel tank & generator / welder in the front & probly half a tonne of steel & spare parts & never had a drama . 5th gear isn't much bigger than a 50c coin from memory ( happy to be corrected as its a long time sine I saw inside a 4wd gearbox ) but if you're towing that's a lot of load on such a small gear if you ask me .

I thought the 5th gear issue didn't apply to the TB45's.
IIRC it was due to a machining issue for the 5th gears for the early GU TD42 which is a different ratio.
TD's are 0.836 and TB's are 0.850

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Originally Posted by the evil twin

I thought the 5th gear issue didn't apply to the TB45's.
IIRC it was due to a machining issue for the 5th gears for the early GU TD42 which is a different ratio.
TD's are 0.836 and TB's are 0.850

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That's the best news yet
I'm hoping that's the case. Might have to adjust my search to find more. I'm going to drop the oil today because apparently I used GL 5 instead of GL 4 and have cold second gear issues since the day of the change so lest hope its not rusty /orange.

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Quote:

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Originally Posted by mjr350

I'm going to drop the oil today because apparently I used GL 5 instead of GL 4 and have cold second gear issues since the day of the change so lest hope its not rusty /orange.

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I have the same issue. Let us know how you go..
I'm 5000k away from 80 thou major service so not to keen to drop oil now and then have it all dropped again in 5000k

Quote:

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Originally Posted by mjr350

That's the best news yet
I'm hoping that's the case. Might have to adjust my search to find more. I'm going to drop the oil today because apparently I used GL 5 instead of GL 4 and have cold second gear issues since the day of the change so lest hope its not rusty /orange.

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All you need is castrol VMX80 comes with the friction modified addative required, as the cold shift issue has been a known issue from day dot

That's what I used previously. Had a look and it is GL 4 but somehow caused the cold second shift issue. Filled with penrite pro gear 75w 85 with nulon G70 additive and its a lot smoother but the previous oil did come out quite rusty looking. Might give Nissan a call and see if there's any history.

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