I have a similiar problem. When driving at 60mph (3000 rpm) and engage the OD, initially nothing happens. If i take my foot off the accelerator slightly, the revs drop to 2000 rpm as if the OD has engaged. However, as soon as i touch the accelerator the revs jump back to 3000 rpm as if i have switched the OD off. I have a 73 mk3 GT6. I assume the gearbox oil / fluid is shared between the gearbox and the OD unit. The gearbox oil is full. I have read somewhere the OD has its own transmission fluid.......
I can hear the solenoid click when engaged (stationary with engine running) in 3rd and 4th gear, no click in 1st or 2nd which is good.
Thanks in advance for any tips
