Complex sentence: There are some minor variations to the above mentioned heads including different thickness cooling fins and thicker centre electrodes on later model OEM glow plugs however the internal shape and glow plug filament remained the same.
Split into simpler sentences: There are some minor variations to the above mentioned heads, including different thickness cooling fins and thicker centre electrodes on later model OEM glow plugs. However, the internal shape and glow plug filament remained the same.