Timing Chain

[2000 GMC]

Sorry if this has been posted before but my internet here in Iraq sucks and I've been disconneted on my last few search attempts. I'll be heading home in few weeks. I wanted my wife to take my truck in so all maintenance will be done when I get home. When I left a year ago, it had 110k on it and I changed the anti-freeze, fuel filter, transmission fluid, front and rear differential and oil. When I was home in Feb I changed the oil. Right now it has 114K and all I think it needs done is the oil and cabin filter which I can do my self. At what mileage do I need to get the timing chain changed out if it's needed? Thanks!!