Using GT 5.09.38 pre3, GT++ 1.4.38alpha.

Both 38alpha and 15release have problem.

Same for GT 5.09.27 :|

That's not a texture pack problem(double checked),

It is the fault of @Blood-Asp.
I haven't touched texture code for this stuff in months, he has recently with his clean room changes.

Oh. Got it. Thank :)

But it is only a visual thing I guess?

I wonder why this issue was opened in GT++ in the first place... There is nothing of it connected to it afaik so https://github.com/Blood-Asp/GT5-Unofficial/issues would have been the right place.
I did build all 4 turbines with only GT installed and have no texture issues. Maybe the texturepack you are using is the reason?

Your texture array indexes overlap mine. That's the issue.

Please test gregtech with GT++ in the future please to prevent index overlaps and other issues.

Sorry to say, but this is at least partly on you, @draknyte1.
The casings are separated into units of 16 and you should have made your casing offset a multiple of that, not 57.
It could be reasonably assumed that the GT5U core mod will at some point add new casings and fill up the remaining slots in GT_Block_Casings4, resulting in a collision.

This is from before your time and will be resolved when I have free time. This wasn't open for discussion.

Fixed in dfb374e.