Volvo Repair: 92 240 rumble, steering wheel, motor mounts

Question
hello,
i have a 92 240 wagon. the prob is when i get going any speed over 45-50 i have a good sounding rumble going. the steering wheel does not shake, car stays true to the road. it goes away   when i take my foot off the gas. my thought was that the tranny(auto) does not engage 4th gear. because ican press the  od button, light comes on nothing happens?  replaced the relay and that did squat.
any tip i would greatly appeciate

Answer
Tommy, the od is engages after the 3rd gear.  When you push the button, you are turning it off.  You may be having a solonoid issue, or the wire may be disconnected or severed.  As far as the rumble, have you checked the motor mounts and trans mount?  Roger