Clunk while slowing in 3rd...

Hey guys, first off, I have an 87 XJ with the AW4 and a D44. The car has 181k on it is in need of a little help. I am rebuilding the engine as we speak and I am waiting to make the final adjustments...Anyway, before I did anything, I noticed a strange thing (perhaps problem?) about leaving the car in 3. If I were to drive around in 3 and then come to a stop while leaving it there, I always feel/hear a slight clunk when coming near stop (like 10-15mph) I don't know if this is normal or not, I am not too worried as the transmission has held up quite well. If this is normal then nevermind, but if not, what would cause this/what can I do to fix this? Thanks!

Possibly your rear axle pinion angle is shifting up and down during acceleration/deceleration?

Or your tranny mounts or engine mounts may need replacing. The tranny will bump up into the tunnel if it's bad enough. My 97 manual tranny did it when I bent the crossmember up a little, during acceleration though.