I finally got my gaskets to pull the exhaust manifolds for repair.
I was wondering whether anyone knows the size of the studs where it connects to the y pipe? M10x1.25x60 Maybe?
Also the size of the bolts holding the heat shields? M6 maybe?

The studs are definitely M10 of some sort. When I managed to get what was left of mine off I replaced them with stainless nuts, with a hefty glob of copper grease.

From under the car I needed a socket 13 to undo the nuts, some nuts came off, some studs came out from the upper part depending of rust.
Soaked it with penetrating oil for an hour or so, then carefully wiggling not to brake anything.

Heatshields are M6 indeed (same story).

You are correct, m10x 1.25 x60, that's what I put in mine

no10chris wrote:

You are correct, m10x 1.25 x60, that's what I put in mine

Looks like I guessed pretty good. Thanks for your reply.

Thanks everybody for the input. Time to go to the fastener store.

Just an update on this for anyone doing this in the future.
Studs are M10x1.5 x 42
Heat shield M6x1.0x15