Right. I am writing an update and authoritive bit of advice on the fuel pump rebuild.
1. You can only replace the pump itself as described above. You cannot change the post-filter integral to the black cylinder unit.
2. Do not try and open the black cylinder by removing its cap, this will break the internal plastic seal and render it scrap.
3. You cannot effectively glue and strap down the previously removed black cylinder cap, it will not hold the pressure.
So if an original pump fails, you cannot change the post filter integral to the black cylinder. The only way to add a new filter is to put one in-line under the car. In this case you would re pipe the pump outlet so it feeds directly up to the plastic head cap containing the pressure regulator, so the original post filter is no longer fed. This might be sensible for a high mileage original pump which has failed, you can get a new pump to fit for £25 and put an in-line post-filter under the car, perhaps the lot for £40, a lot less than a new pump unit from the dealer.