Thread: Knocking sound

First and reverse share the same gear, and the symptom suggests the gear has a damaged or missing tooth. This will not affect the other gears.

As this is in the main gear box and low range is in the transfer case, there is no connection. The transfer gears can be inspected by removing the bottom plate and having a look - my guess is a selector problem, perhaps the selector fork loose on its shaft.

It is not as easy to see what is happening in the main gearbox, although you may be able to see something with the top off, or drain the oil and check what comes out for bits of metal. However, to fix the main gearbox, it will have to come out.

John