You should be able to use the
Huztl 24" 84DL bar for Husqvarna if you make an adapter. The Echo uses a D176 mount just like the G621 clone I showed upthread - the slot in the bar is a bit wide (I think the bar is a D009 mount), but the oiler holes work. I made an adapter out of some stainless flat stock from an old wiper blade, but there are other ways to do it. You can use it without the adapter but the bar can rock a considerable amount.
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I would caution you though that after the paint wears out of the bar groove in about 30sec the 0.058" chain will probably flop around like a fish out of water, and you'll want some 0.063" chain. Still, a loop of that is only another $9. Even the CS590 will be a bit nose heavy with this combination, but quite usable.