Well, looks like no winners this time. Tranny mount wasn't broken, but I replaced it anyway since it was so oil-soaked. LCA & UCA bolts were all tight. Clunk still there. Surprisingly, it appears to be the front driveshaft u-joint, at the axle. Surprising, only since it clunks without being in 4wd. Work to do next weekend! Thanks for all the suggestions!
Jim