I check all bushes up, they are in good condition, unless drivlinebushes on diff and on driveshaft from gearbox to rear axel, i replace all of them.
On pan to 5 gear it is a tube on inside pan, the small tube vas blocked with dry paint,
maybe that caused problem with lubricating. I also overfill gearbox. Now its like cutting butter when shifting. I weld tube on oilfillernut and a hose up beside radiator so i can fill oil from there.
I like that filler tube idea, I may have to look into that, if you used a clear tube you could prevent overfilling.
I forgot to mention, it sounds like you may have a 4x4 so make sure you change the fluid in the differential and clean the vent out, they often get overlooked.
Another issue is vacuum lines, if you haven't already done so, replace them all with high temp silicon lines. If you check my garage you will see a list of my repairs and modifications, parts lists and suppliers. You may have to use different suppliers on the other side of the pond. Leaking vacuum lines will cause you all sorts of problems.
You have to do so many posts, I think it's 5 before it will work. The best way I found to do it is to add them to an album and then copy thee "BB" link to your posts. That way if you want to use a picture in multiple posts it won't add to your data usage each time you post it.