I have an old (apparently there is a new) Echo 400 EVL. I bought it in the mid? 80's. Is there a major difference between the old and the new? Mine still runs good but I'm not sure what the best chain is for it. It has a 16" bar. I currently use a Stihl 23RMC3 66E chain. Is there a better chain? I'm not a professional logger, just use it around the farm. Thanks