Re: Exhaust manifold turbo mounting studs
The studs and nuts are a special heat resistant alloy material. I dont know the exact material used, but suspect that they are an inconel 600 type alloy. The studs (and nuts) fitted to my Ty came out easily even after being in there for 20 years.
Personally,I wouldn't just fit any old stud in there, not if you ever think you will want to guarantee being able to undo them easily again.
If your post dosen't turn anything up, an internet search should bring up something from another vehicle that would be suitable. Standard M10 (coarse) x 38mm long if I recall, but dont quote me on the length. The nuts are automotive oddball too, being 15mm AF, smaller than the standard 17mm you get on M10 fasteners.
You need the 15mm nuts, or you wont get a ring spanner (box wrench?) On there.
At worst, you could get some made. Inconel 600 is commercially available in 17mm round bar in the UK, from that you can machine the studs and manufacture a 15mm hex from that diameter for the nuts if required.
I suppose it depends how keen you are.