does an k reg 1.8 estate have the type 9 box and if i connected it to a 1.6 capri axle could the axle cope okay

Yes, all sierra's have the type 9 except the later 2.0 twin cams which have the MT75.

The salisbury axle will handle any amount of power you could throw at it, its other name is the atlas, I have heard they use it in rallying and will handle 200BHP plus reliably all day without any problems.

If you use the capri axle, make sure you have the propshaft, the sierra prop will fit the axle no probs, but the grear box end has a dirty great rubber donut which you cannot use. The capri prop has a U/V at the front which is ideal - I know cos I am searching for one now!

I've got one.

As I said in that other thread though, I'm in Lincolnshire...

Is that anywhere near England?