At the tail pipe you won't see any evidence of the engine burning oil. It's the blue smoke screen that you leave behind that's telling.
If the diesel starts well in the cold and has reasonable power - all 68 HP - then the rings and compression may be OK. You didn't say how many miles are on this engine, if over 250K it may well be worn and the oil burning is a sign of that.
You've evidently tried to fix some oil leaks with new gaskets. This engine has only a few leak sites, valve cover, bottom cover and the crankshaft seals - front and back. The vacuum pump on the front of the engine is another possibility.
Blow by is from combustion by-passing the worn rings and creating pressure inside the engine that forces oil to leak from the above mentioned sites.
On the top of the valve cover is a hose to carry the crankcase fumes to the intake manifold for disposal. It could be that this hose is clogged and/or that the screen inside the valve cover is so dirty that oil that should be drained off is being forced into the intake manifold and consumed. This is more possible if the engine runs too cold - without a
80 degree C. thermostat.