Hey D, loving the M16A.

Here goes nothing, this will probably confuse you rather than give you a picture of whats going on.

The symptom is a violent vibration through the whole car when you back off the power or when you cruise up to 80km and back off to just coast. It gets worse if you put the clutch in and roll at 80km and is also very bad coasting in 5th.

Through process of elimination and coountless hours off looking we have narrowed it down to the tail shaft. Had the car up on stands in gear and it just doesn't look right. With the car on all fours I have too much play up and down where the tail shaft slides over the output shaft on the box.

The shaft could be too short. So I un-bolt it from the diff and slide it in and the play becomes acceptable, I slide a touch further and it hits webbing on the box. I then notice witness marks on the very front yoke and the grease nipple has worn down where it has contacted the gearbox. Its hitting as the suspension travels and diff kicks up.

You really need to know what a sierra box is like. There is a large section for the gear selector the sits above the output shaft. So a good 6 or 8 inches of shaft along with the uni's spin under the gear selector.

So i'm thinking the shaft is too short and causing vibration. Sierra's run a remote transfer case with a short shaft thats bolts to a flange on the transfer case. The short shaft and box must have little clearnce as there is very minimal movement. Its not coping with normal suspenion travel.

Whats your thoughts?
Do you have any idea what I just posted? because I don't