I had the exact same thing happen to mine , an lt77s which had the r380 gears with the intermediate type synchro rings, the oil ran low over a few months and it gradually got noisier
The Input shaft had the same blue tinge so I binned it all as I didn't want a potential tooth weakness just waiting to show up catastrophically , not only did they get mega hot but also the casing had a blue haze around the bearing! , ended up fitting an sd1 2.4 diesel gearbox in its place which also leaked oil so investigating transit 2.4 gearboxes currently as they have normal ratios compared to the 2.5 Di
