when i start moving from a stop, a very loud clunk is heard and felt. it sometimes shakes my whole truck. i know it is not a u joint, ive checked all of them. i thought tranny mount because the noise only happens once until i stop again. which would say to me its a mount or suspension part. the tranny mount appears in good shape. i looked at it closer and discovered the bolts on the bottom of the mount were loose. so i tightened the crap out of them since ive noticed this before. but never in the past have i had a clunk. which leaves motor mounts. and they are tricky to look at for whatever reason but they appear good as well.