Is there a difference/compatability issue between an 'old' LT230 and a new LT230 input gear ?
Are there different sizes does anyone know ...

Think they are the same.
What’s the problem?

There are differences. What are the ages of what you have box wise?

Am not allowed to fit this myself so a good friend (James) is doing it for me.
These are his words and pictures...
//
When I tried to fit the gearbox to the transfer box it jammed up with about an inch to go. I managed to get it off again, removed the input gear from the transfer box and the gearbox fitted fine. However, the input gear jammed up on the #3 gearbox main-shaft splines when I tried to fit it. I tried the input gear on the old gearbox (#2) and it fitted perfectly.

The new gearbox main-shaft has quite a bit of pitting on it, so obviously not a new part and I initially thought it was the pitting causing the issue but looking carefully at the splines I can see a slight twist in the main-shaft. It’s only small but I think that is what's causing the input gear to jam on the splines. There’s no wear or fretting to the splines on either the gearbox main-shaft or transfer box input gear. I’ve attached a few pictures of the main-shaft splines with a straight edge but it’s difficult to get a good measurement over a short length.





Not sure what the ages of the boxes are, will get some serial numbers (if that will help ?).

So you have two input gears, do they look identical? Are they cross drilled types? I do not see a twist in the shaft though, the rule will not sit straight at the box end because the spline grooves shallow out and widen there, it is just the way they are made.

tottot said:

So you have two input gears, do they look identical?

Click to expand...

Two gearboxes (R380) and one LT230.
In fact this is gearbox #3.
No problems with the original, #1 or #2.

What is the difference with the input gears ?
Is this documented somewhere ?

There are several differences, an example is early none cross drilled input gears have shorter splines inside.
Ashcroft site "ashcroft lt230 input gear" for more info.

Input gear from my LT230 (22D135008D)




I believe this is part #FTC5089

Here could be the issue ...
Different main shafts ...



The more recently supplied gearbox has a longer main-shaft.

I recon so. Likely you will need a different input gear. I do not know what the various part numbers are, much info on Ashcroft's site.