Troopcarrier problem .

Hullo Mark
Might be worth while having a look at the lcool site. (lcool.org)
There is a section for 70 series Cruisers
Only takes a short while to join (free) and you can tap into a group of very knowledgeable people
Cheers
Andrew

could be a restriction of some sort in the exhaust, can cause a whistle at certain revs

Transfer case more then likely case hardening has came off bottom sharft and gone through box,very common.

Try Troopcarriers of Australia Facebook page. I have had plenty of input/ideas for my Troopy

Mark,
You say whistle so I am thinking it could be a leak in the exhaust/manifold. Have you disturbed anything associated with the exhaust recently? Look around the manifold and especially where the exhaust pipe comes off. They do tend to crack the weld around the flange if the support brackets have not been set right.

If it is more a whine then there is a well known problem in the gearbox/transfer which is much discussed on LCOOL. If you think it is this then do something soon as it gets more expensive if left.

Morning Mark.
My 80 serise aquired a whistling sound in all gears when driving and it turned out to be the ribbed fan belt, happy Australia day Mate.

Did the noise only start after the exhaust was done?
Is yours turbo?

Could be the sound of the turbo, quite often the whine becomes noticeable after adding a snorkel or free flowing exhaust.