I think the testimonial match took place in 2005, so it might have been a mishmash of players from the title win and players who he was particularly friendly with since?
The 1997/98 players who made at least one 1st team appearance that season were....
Baraclough, Ian (1995-1998)
Cunnington, Shaun (1997-1998)
Derry, Shaun (1996-1998)
Diuk, Wayne (1997-1998)
Dudley, Craig (1997-1999)
Dyer, Alex (1998-2000)
Farrell, Sean (1996-2001)
Finnan, Steve (1996-1998)
Hendon, Ian (1997-1999)
Henshaw, Terry (1998)
Hogg, Graeme (1995-1997)
Hughes, Andy (1998-2001)
Jackson, Justin (1997-1999)
Jones, Gary (1996-1999)
Kiwomya, Andy (1997-1998)
Lormor, Tony (1998)
Martindale, Gary (1996-1998)
Mitchell, Paul (1997-1998)
Otto, Ricky (1997)
Pearce, Dennis (1997-2001)
Pollitt, Mike (1996-1998)
Poric, Adem (1998)
Randall, Dean (1998)
Redmile, Matt (1995-2000)
Richardson, Ian (1996-2004)
Robinson, Phil (1996-1998)
Robson, Mark (1997-1999)
Stevens, Shaun (1997)
Strodder, Gary (1995-1999)
Ward, Darren (1995-2001)
White, Devon (1997)