In reference to the T3 4-bolt style on the turbine side outlet of the turbo(Garrett GT's, turbos, etc). Is there a difference? I've searched and search, and nothing seems to come up. But just lists the T3 4-bolt and T31 4-bolt being the same? BUT I read somewhere that the bolt spacing is different from each other. Can anyone more familiar with this clear this up? Thanks!

 

You are correct. The standard 4bolt t3 is at 3" spacing between bolts while the t31 is at 2.5"

 

I see, since it's only .5" difference. Are there more turbo options to choose from over the other?

 

Not really. 3 inch downpipes typically are flared from the standard t31 2.5 "

 

I see, also anyone here familiar with the Holset HX35 turbo? Anyone know
what bolt type, length, and thread pitch I need for the oil drain flange?

 

Those are still 1/2" from what I remember. Check with stealthmode.com to verify.

 

hmm Ill check that out. I can't seem to find out that last bit of info anywhere