Screech and clunk sound

Hi All, I have a 1998 GU Patrol TI, i havent had the vehicle long but have noticed of late (not sure if it was always there since i had it) but when i start the car in the mornings and start driving after about 3-5 minutes i hear a screech and clunk noise coming from underneath i thinks from the gear box may be (guess) it doesnt affect anything and car drives fine only happens once, if i drive the car throughout the day its doesnt reoccur however if i leave the car most of the day at the station and when i get back after work it as only happened once on the way home? could be done to a cold start as temps have started dropping in the mornings here in Perth. Any ideas?