Dan, Its kind of a yes and no thing with the Poulan/Husqvarna bar swap. I had some round wire spacer thingies, I think I got from Mark long time ago, that made them fit the bar studs. My problem with switching Husky bar & chains to a Poulan is the drive link count. Swap directly and the chain will be to long on the Poulan. I have one 4000 that I keep a 24" Husky on, that just works. All other I have tried , just to long to adjust. Hence the 72 & 70 drive link difference mentioned by Hotshot.
So if you get a shorter chain, it will work. Trouble is, now you are usually dealing with an oddball length chain and .58 gauge as most Huskys are. So my answer is yes, you can set a 4000 up to run a Husky bar, but not easy to just swap directly to a Poulan. I think Poulans bar studs are located closer to crank (clutch) than on Huskies.
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