<Yes, the head widths are different, but I have always been under the <impression that using the /f or /f:360 switch with format changes the wri <current on the drive to adjust for the different coercitivity (sp?) of th Assuming the drive/controller are correctly configured. My FD55Gs have three different jumpers for write current, speed and a dual function one. Of course the media must match the write current/speeds. The narrower head is a big factor as it is optimized for a narrower track and the gap dimensions are tuned a bit for that. When I first encounterd it I could not understand it and then I O'scoped a pair of drives and the read on a 360k(48tpi) drive data from a track written on a 96tpi and the data waveforms were terrible. Too much noise from the periphery of the adjacent track and effectively less than half the magnetic strength imparted on the read head. Having played seriously with magnetics the media and head do have to be matched. This however does not solve the posters question. My cut on that is if the media was created on a know good 360k drive and it doesn't read right on a unknown drive, one of them is broken. ;) Allison