Transmission

I got my 2008 jimny (75,000 miles) in october 2024, Absolutely in love with it and the perfect fishing vehicle, however my transmission is well and truly finished off I bought it from a lady just outside of london and the gearbox felt alright at the time, it was never very smooth from when i got it so I changed the transmission fluid and the amount of metal in the oil was very alarming, currently is undriveable and slipping out of 1st so i have ordered a reconditioned gearbox which I'll be fitting, has anyone else done this before? any tips? 
Thanks

Many of us with the R72 gearbox from 05 to 09-ish done this. Only a few if any with the other boxes.
Before 05 the R7me gearbox had other ratios making it stronger and with longer bearing life.
After 09-ish the bearings where changed to closed ones wich seem to make the bearings last longer.

When you have the gearbox out it is smart to check or just as well change the clutch while you are at it.
And maybe the clutch wire too.

There is a how too in the wiki but it relates to the R7me gearbox. The R72 swap is a bit easier as it can be taken in and out without too much trouble. I done this a few times lying on the floor of my garage with the car on axle stands. It is not easy though but doable.

Thanks, will let you know how the swap goes, will swap out the clutch whilst I'm working on that part of the car as I'm driving it to Germany in June.