I discovered something a bit worrying today. My trans is out for a rebuild - a saga on its own! - and I had the tank dropped - another saga! - to investigate the filling problem. The workshop found a nest of hoses lying on the top of the tank, which proved to be the vent hoses for the front diff, trans and engine. No collector box, no check valves, no nothing - just lying there.
If ever there was a dust and muck trap, it has to be the top of the Syncro tank. The great worry is that these pipes do indeed breathe. Air is expelled as the diff, trans and engine warm up, and it sucks back in when they cool down. The danger here is that dust and muck will suck into the breather pipes. (The workshop, on their own initiative, is routing the pipes into a single pipe and running it up into one of the rear pillars.)
I haven't cross checked on ETKA yet, but someone might know if they were ever fitted with check valves or any form of protection.