I almost ordered a new BT-43EI when I accidentally noticed a BT-43EI-2 is available for a few dollars more. I saw that the EI-2 had a black muffler instead of a silver one, but what are the other differences? Are these FIXES or IMPROVEMENTS? Noticed a few other parts listed seemed to have different stock numbers. I am going to wait to see if I want the most recent version of this engine. Thanks for the help and the information. Roger in Colorado