Which Defender variants can you remove the hard top from?

[NDT]

I'm thinking about getting a Landie as my station car.
I was going to go for a classic series car and run a tilt in the summer and hardtop in the winter, but I've seen the occasional Defender with a tilt as well.
Does anyone know at what year they started spot welding the top on rather than bolting it like a Series Land Rover?
Is it all Defenders?

[NDT]

Cool, thanks for that Pete.
Probably go for a recent one then... i.e. younger than 20 years old...