Spent some time flying these in Africa.
Make Sure EGT gauges are serviceable, there about you best indicator which engine has died.
Rear Engine Cycles fuel faster than the front. Watch out for sticky fuel indicator switches on the fuel selectors. Easy to think you've got more than you actually have.
Some 337's have dual hydraulic pumps, but in the event of engine failure feather the engine first then worry about gear and flaps.
Lead with Rear engine (Right throttle) first Up to full power, The slowly bring in the front engine.
Rear Cowl flap needs to be open a crack in the cruise unless its below 0 to 5 degrees c.
Don't try a haul it off the ground to early the drag will kill you.
Single Engine Performance is respectable, Rear Engine Better than Front.
If someone accidentally bangs the tail on the ground, check the gap between rudder and fin its fairly tight.
Mirrors on the boom to check the u/c gear are in invaluable.
Probably more there but my grey cell in tired.
Cheers
snips
One more, The aux tank pick ups uncover fairly easily leading when not in normal climb decent turn, S+L etc and leads to a raised heart beat
