"Is it: Chassis mounting end, thick washer, shock, thin washer nut.
Axle mounting, thin washer, shock,thin washer nut? "
As I understand it..
Yes to chassis end, but note that the recess in the thick washer faces the chassis mount, not the damper. The recess is there to provide clearance over the stud's inside fillet.
It is important that only the inner metal spacer tube of the damper mounts is clamped, and not the rubber itself, as that has to be free to flex with the suspension's movement.
Axle mounting : perhaps.. The large thin washer under each nut is a safety aspect ..in case the rubber bush shears - it prevents the damper end from dropping down onto the road. It is under each nut. But, where there is a suspension arm bracket / plate then no first washer is needed, only the thin one positioned under the nut.
So.., the first washer may be omitted or may be a thin or a thick washer ..according to alignment of the damper between the chassis and suspension arm. Some aftermarket dampers have a different length of metal spacer tube inside the rubber bush. So, pinch the chassis nut up to see if the damper aligns ..if not then shim front or back accordingly.
I hope you also realise that the damper's nuts should not be tightened up until the car is resting on its own wheels, or blocked up under the end of the axle arms.
The reason for this is : If the damper's nuts are done up tight when the arms are hanging down at a -35 degree angle, then when the suspension arms rotate back to horizontal (thanks to the car's weight) .. then the rubber in those bushes would be twisting / in torsional shear, which is why they prematurely fail. But if they are (correctly) tightened when the car is sitting on its suspension / carrying its own weight - the rubbers are unstressed in the static condition, and then have enough articulation when twisted either up or down, with the rotation of the suspension arm mount
Hope that helps.
Pete
NB. edited to correct my grammar !