I had to push up on it just right to make it clunk. It was my second attempt before I caught the slack in it. It may be the bearing which is on the forward end of the extension housing. The snap ring for the bearing did not show up today, so must wait another day to tear into it. I ordered the extension housing, seal, bearing, snap ring for bearing and speedo sensor o-ring. If yours is doing the same as mine, your muffler, fuel tank and bottom of cab is covered with ATF, but no visible drips overnight. I changed the seal and fluid in June, filled it at that time, and was down almost a quart last Saturday so pretty sure I'm onto it. Will let you know. Also, filler plug is lower than extension housing so it must pump fluid up there when in motion. I would not think splash lubrication would cut it.
Mike