1996 chevy 1500 4x4

[stonecold]

ive got a 1996 chevy 1500 4x4 and cant get the front rear to kick in. what could it possibly be? it is floor shift for four wheel. some kind of sending unit or????????????????? any info would be greatly appreciated.  thank you

 

[fubar818]

not sure of the name of the part but their is a silonoide on the front diff it may be bad maybe

 

[stonecold]

ttt and thanks for any info