Green or white gearbox inspection plug

Anyone know the difference? I have a green one but it doesn't seem a very good fit, I'm wondering if I should have a white one?

It's a 1983 Mk1 GTi tintop  with a DX engine and original 020 box.

The 2 gearboxes I have off 83 GTi's had green ones.

Even the original was a tight fit which is why you have to struggle getting it undone without destroying it I've taken to only screwing it in till it's just catching, it does stick up a little but keeps the dirt out.

I put a little silicone grease on mine to help with removal.

That makes sense Mark, thanks.

white one is for 190mm & 200mm clutch, green for 210mm clutch.

but it doesnt matter to you, the reason for the difference is so the special VW timing adjustment equipment is spaced the correct distance from the flywheel.

It picks up from those odd square casting marks on the flywheel, if you've ever wondered what they are for