I need some advice.95 e250 started with ign. Lock cylinder.replaced it,ignition switch replaced it,2 batterys and a third starter.something is taking all the juice.where to start

 

If there are no add on's , make sure all lamps are out including glove box lamp if it has one.

If you have no test quip to measure current being drawn when all is supposed to be off, one thing you can try is pull half of the fuses, keeping tract of where they go.
If you still have a drain reinstall the first half bunch of fuses you removed and now remove the other half and see if it still drains the battery.. With no equip this is the hard way, but still works. Once you have some idea of what the batch of fuses you last pulled controlled you can narrow it down to one particular fused circuit.
At least now you have some idea where to start checking without having to go over the whole vehicle.