There are 3 slots that you can research manufacturing for but they don’t show up in the slot GUI: trunk, hood and valves.
Found one more. I can research fuel tanks and on the slot GUI fuel tank manufacture is an option but it remains grayed out after research is complete.
Fuel tank unlocks flywheel if I remember correctly
Yup this just got fixed! (cant remember if it was in 1.03 or i’ve just done it for the next patch tbh…)
I just used 1.03 so it must be next one.