What's the difference between a series 2 and a series 3 bellhousing?

I am about to order a new chassis but need to know What's the difference between a series 2 and a series 3 bellhousing so I can get the correct crossmember

The clutch slave cylinder on the 3 is bolted straight to the housing.

I think, not certain, that this meant the crossmember has a bit more space.

The 2a clutch slave is on a bracket.

If I remember, I'll get a compare and contrast photo tomorrow.

Get the crossmember that suits your gearbox.