Gas guage problem

[Bub63]

Hi all I have a 98 Tahoe today the gas gauge started going back and forth from full to empty while driving when truck is off it goes to empty like always my question is how can I tell if it's sending unit or the gauge has gone bad ? Also is there places that will refurbish the gauge cluster ?

 

[exp500]

Test at tank, test at dash.
Ebay sellers fur refurb.
See Helpfull links in 91-99 section.