Hi,
What is the measurement of the bolt or stud between the manifold and the downpipe? They're missing 2 on both sides and is leaking big time.

 

I soaked the manifold bolts in pb blaster, took two cans over two days- removed the manifold, drilled out the hole on the manifold then in the y pipe- the y pipe has nuts that will come off after you've drilled them some- re assembled with the same gaskets as they were in good shape, now i have a 6/16 grade 5 bolt/nut and its back to being quiet.

 

They are M8X1.25 studs. Not sure of the length.

Land Rover Exhaust Manifold Stud Kit | Land Rover Exhaust System Parts