Haven't dug too deep on it, so can't tell you the thread size/pitch - but here is a link to them for purchase. You'll need a thread checker and/or calipers to get the size and pitch of the stud.

90179-08012 Genuine Toyota Nut

 

The label 350 (25, 34) refers to the torque specification in different units. The middle one is in foot-pounds or 25 foot-pounds. It's a pain to get to these nuts when torquing. I had to use various lengths of extensions and a universal socket adapter to get to them. You have to dodge the waste gate actuator rod without damaging it. Here is a link to the online manual, if you weren't aware of it. Click here to go there.

 

m8x1.25

 

Usually just take these things to the local hardware store and use their bolt measuring chart.