I myself have seen the small DSO buck tag only in the 1985 model year, for OSP (FF206xxx VINs) and UHP.
Although tough to make out in this pic, here is the UHP (206xxx VINs):
http://www.specialservicemustang.net...info206805.htm
Later in the year (FF234xxx VINs) OSP got 'normal' size DSO buck tag:
http://www.specialservicemustang.net...info234942.htm