I was putting my dad's Poulan 361 back together tonight when I broke a piston ring. Yeah I know, I was trying to do it without the proper tool, will order one from Bailey's, but I first need a new set of rings. Every site I checked said they were obsolete, but surely someone out there has a set. They are part no. 2577 (old number) or 530002577 (new number). The cylinder bore measures 1.788" (45.4mm) x .062" thick (1.57mm). Bailey's sell rings that are 46mm x 1.5mm and I wouldn't any problems filing the end gaps to fit, but I not sure about the rings being .003" thinner, which would give about .004" clearance in the groove. These rings are also the same as a Poulan 306A.