Well now you can do exactly that! With this copy of GregTech 5 Unofficial, you can load GT6 at the same time! Now you can enjoy GT5u’s endgame and GT6’s earlygame! I mostly did this as an experiment to see if this was possible. This is an exact copy of GT5.09.31pre1.
Warnings and disclaimers:
This requires a very good computer to run! As you can imagine, it will be very laggy.
To prevent this lag, I recommend using Chunk Pregenerator.
Do NOT report any bugs with this to GregoriusT or anyone who is still working on GT5u (only one person from last count)
You will probably need to fix enchantment IDs for this to work.
You need IC2 to run this.
There is no GT5 worldgen.
I recommend starting a fresh new world for this.
GT6’s tech tree can be circumvented easily with this mod! you have been warned.
GT5 pipes and cables cannot connect to GT6 pipes and cables!
If you need to transfer power between the power systems, use IC2 battery boxes to do so.
GT5 and GT6 pipes may connect to GT6 tanks. (not tested)
GT++ will NOT work with this!
GTWW and QwerTech will probably work (don’t quote me on that!)
I will most likely not be updating this in the near future.
New GT6 builds may break this mod.
I do not claim responsibility if this corrupts your world.
You are using this mod AT YOUR OWN RISK.
TL;DR: if this mod fucks you over it’s not my fault
After reading that, you may proceed to the download:
GT5u for GT6 Download
Discuss on my discord
My Patreon
Don’t forget to post anything cool you build down here!
Have fun with the fusion reactors 
