transfer case in neutral?

im trying to isolate that whining noise, i need to get the transfer case in neutral but dont no how. i dont have an owners manual and the dealerships aint much help here. i have a 1997 gmc z71 with push button 4x4, it only has 2hi 4hi 4lo, no auto shift, does someone know how to put the t-case in neutral?

not 100% sure for this year how to...for newer models trans in park or neutral key on. press 2 hi and 4low buttons and hold for 10 seconds...it will roll...even in park so be prepared to apply brake

Thanks for the input, but according to my many failed attempts and the dealership here, in this model there is NO neutral. if it has to be towed from the front the rear driveshaft MUST be removed.