Loud metal clank when putting in park
 

Have an 01 excursion xlt 2wd 6.8L v10, 210k miles, when its cold outside and truck hasn't warmed up all the way, when I put it into park after moving it, it makes a loud metal clunk sound coming from the side opposite air filter so right side from seat. Once engine is warm and has been driven for awhile it doesn't do it at all. Location of sound could be wrong.

Anyone have any info on what to check for. Just really hoping tranny is good. But sound is troublesome

Not always good to suggest an unsafe procedure, but what is sometimes done is; open the hood, have a second person walk alongside the vehicle while very slowly moving the vehicle and then have them attempt to determine if it could be coming from the drive shaft u-joints or inside the engine compartment.
Another alternative is to have the vehicle inspected on a lift to see if there are some worn parts beginning to show up.