Hey guys, I have a case of a fried ecu. it is an M ecu and I have found a few CH ecu's on ebay, audizine, etc. Are these the same? I read in a description that the two are interchangeable, but i want to make sure. Please respond. Thanks!

 

anybody? This is for a 2001 a4 1.8t tip. my oem ecm is 4b0 906 018 M and I have found a few that end in CH. From my research, the M's were for early 2001 models and CH was for later models. Are these interchangeable?