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Putting back a Series gearbox and keeping the Disco axles?

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Hi all, I bought a Series IIa SWB 1962 about two years ago.

The car was modified by previous owner, it has Discovery axles and Isuzu 4jb1 + isuzu gearbox fitted. 

A friend of mine is able to provide me an original engine and gearbox the question is: how (bad) will the Disco diff ratio fit with the Series gears? I understand it is a higher ratio.

I cannot easily put back original axles as the leaf spring mounts have been relocated more on the sides of the frame to clear front diff and solve the steering linkage issue.

I'd like to put back an original petrol engine what would be your advices regarding compatibility with the Disco axles, Shall I put the Series diff gear into the Disco axles or are there any other way around to restore the overall gear ratio while keeping the axles?

Sorry if these mods hurts to read, I bought the car as it is, but miss the LR originality and petrol engine comfort. Your advices are greatly appreciated.


(picture of my truck)




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First welcome to the forum. Put the series diffs into the Disco axle providing the half shafts are 10 spline, however your vehicle will be ok with the higher ratio diffs in, these will give better economy although you will increase the gear changes on the hills regards Stephen

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As above, I can't tell if they are thick or thin mushrooms on the axle halfshaft ends. Pull a rear halfshaft and count the splines.

Re the axles, it looks like they previous owner has used angled spring shackles to get the width at the rear of the spring only. If that is the case then a change of shackles should/could allow the use of standard axles?


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I am running a 2a fitted with a 200tdi with std gearbox and tranny box but with disco diffs and 235 tyres and it does pull quite well in second and will just about reach 70 mph so i now need an o/d so i don't see why it shouldn't fitted with a 2.25p engine but it mite take longer to get to 70 mph, hope this helps 🙂

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Is that the 2.8 or 4 litre Isuzu? Actaully... either way, the Series gearbox will really not like that and is likely to be pretty unreliable. The later 5-speed boxes will just about live reliably with a 2.8 4-pot diesel but the Series box is really not built for that - it was designed for an asthmatic 4-pot Petrol lump circa 65hp.

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Thank you all for your response, 


yes the 4jb1 is 2.8L, initially when I bought the car I had planned to try to fit a Defender gearbox to it, as the Isuzu gear box is not a good option for LR (rear output shaft is in the center not on the right side like on LR) but Defender gear box are expensive and rare in Thailand so putting back the car to stock specs with an original engine makes more sense I think.

If my axles are not 10 splines will I still be able to swap only the crown and sprocket to fit within Disco axles?

I assume nothing is straight forward when it comes to changing gears set on such items...




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