Fourth time the exhaust manifold gasket has needed replacing

As the title reads. My exhaust manifold gasket on my 2.5 td def 90 keeps blowing. I've had it changed four times. I've had the exhausts securing bolts adjusted and re adjusted. Even had a garage take the securing bracket off on the down pipe because it was apparently twisting making the manifold not line up. Anyone else had this problem and if you have how have you fixed it????

Also the thread on one of my turbo studs to the exhaust manifold has, for a want of a better word, disappeared. Do I need to take the manifold off and re stud it or can I do it in place???

Thanks for any help.

i suspect the manifold has been cooked and has distorted so the flange faces are no longer in line and won't tighten down properly.

Plate glass and grinding paste or local machine shop should be able to make it true again

Thanks guys. Will get onto it soon.