Transmission to transfer case bolts coming loose

[Tennesseechevy]

My bolts that hold the transmission and transfer case together keep coming loose. I have tightened them 3 times in the past month and even added lock washers and they still will not stay tight. Should I lock tight them or does anyone know what is causing this? Truck is a 05 lly

 

[mike diesel]

I'd guess someone tightened them so much, it has started pulling the studs out of the transfer case, or you have a severe driveline vibration that is soon to cause havoc.