The 94 Discovery 1 I have, the Distributor cap is held on with a couple of snap-springs. You just kinda flick them off and they allow the cap to be lifted up and off. No screws. You then have to snap them back on to hold the new cap in place. The distributor cap has a "key" on its underside. It will only seat in one position.

 

Thanks for the info Phototone. Sounds easy enough. How will I know which plug wire goes to which post on the cap? I looked on the wires and figured out which wire goes to which plug. Starting on the right side of the motor is 1,3,5,7 from firewall out and on the left side it's 2,4,6,8. Do I mark the cap somehow or is there a pattern on it? Thanks

 

Here is what I did. Firstly, I replaced the plugs and wires, one at a time and connected them to the old distributor cap. I made sure the engine ran correctly after that. Then.....I individually transferred one plug wire at a time to the new distributor cap. You should have enough wiggle room to raise up the old cap enough to put the new cap on, and then transfer the wires one at a time. Of course most of the available service manuals and Rave CD download will have a diagram showing correct installation.