make locomotive less wide to make it have a correct size because it is very wide not like in old factorio

Not sure I understand

It looks too long when on a straight track

Sadly that's how the old train is, I would need the original 3d model to fix that. I can change the internal size of the train but that messes up the train stops so this will have to do for now. I am planning on remaking this mod however and I'll see if that is possible.

You can use the same as in Armored Train (turret wagons) mod

Size is fixed in the latest update.