Sounds like the right-angle tranny output to the driveshaft. It should be engine-oil hot, not RED hot, as, to the best of my knowledge it is lubricated by engine oil. Checked that lately??
You should be able to touch it but probably not for too long. I've never done that, but being an ex-BMW-owner I frequently check the final drive temp and that's how that is.
worst case might be bearings and/or gears going in the right angle drive???