I recently purchased a 2-cylinder Maytag gas engine, Model 72-D, serial no. 5520. Can anyone tell me when this engine was made? Also, what brand and number spark plug should be used? There is no muffler and maybe it did not need one, but if it did, is there a replacement for it (original, not after-market)? I would also like the manual for operation, parts book and troubleshooting instructions. Frank Kuehl, 724 Congress St., Neenah, WI 54956.