Tighened up the bolts and the vibration seems to have gone away. As soon as it stops raining(!) I'll put locks on all the bolts and retighten. I suspect the guy who worked on the tractor didn't tighten them properly. If the vibration returns, I'll know it's something else. Right now I am into replacing the rockshaft seals on the hydraulic system of a 1950's vintage JD 420 which is taking up my shop space. Of course, one of the seals is N/A and nobody can match it. The newer seal has a larger OD. So I guess I'm going to have to have the housing bored out to take the newer seal. Another one of those 48 hr. projects that turns into a 30 day project <!-- s:? --><img src="{SMILIES_PATH}/icon_confused.gif" alt=":?" title="Confused" /><!-- s:? -->