Based on the model number you posted. Your saw has points and condenser. It's an older Poulan S25DA chainsaw. The part number for the coil is 39022 and may no longer be available. You could check Poulan / Weedeater dealers for one and maybe get lucky.
Are you sure the coil is bad and that the problem is not the points?
i have a coil here that is nos part only problem is surface rust on the core and the spark plug connector is missing but youcan have this coil for $ 6.00 plus shipping its a 39022 and if i can locate the other two i have in a bag those are intact ones ones already sold but will have a extra one once i find what i did with the package