Overdive engaged ?

[diff-breaker]

Is there any tell tale signs that the overdrive has engaged as fitted the unit but I thought the engine would not race as much but doesn't seem to be any noticeable difference ? Anyone help ?

[dave_2A_2.25Turbo]

Its just like having another gear.  Theres low neutral (sort of!) and high..

I take it you have got the linkage etc not just the O/D unit?

[dave_2A_2.25Turbo]

If the revs are the same, you're in Low, pull the lever back (use the clutch) and the revs should drop

[Rich_P]

If you have an overdrive fitted, you should also have linkage arm system.  Pull the lever back, should dis-engaged the overdrive, push it all the way forwards, it should engage overdrive.

There is also a middle-position which is neutral in the overdrive, and therefore no drive goes to the wheels.

It is not recommended to engage Overdrive while in 1st and 2nd, and perhaps not even advised to be used in low-ratio as it can overstrain the gearbox on lower gears.