I was battling with the carriage with wheels and it was not sturdy enough. I needed a quick fix. I had a MGN12 rail from another printer but i didn't use it so the quickest was to create a mount that the original front and back carriage could fit on.
I added a new X end stop due to the offset of the end stop with the new mount.
This is it!
I used M3 10mm to secure the top of the carriage and M5 55mm (i think) for the bottom part.
EDIT: I added a 12C and a 12H version of the top rail.