I'm so not the kind of chap who has the guts to do this sort of thing, but fitting completed and very happy
I started the project a little late in the day so had to move forward pretty efficiently before running out of daylight. Here is a picture, but its basically just like any other Berlingo with this as a factory option:
The Citroen or Peugeot part numbers are 8742Y8 for the lower part/attaching bracket, and 8742Y9 for the upper part/cover. Bought from Citroen in France for £157, delivery was roughly £11 with their 48 courier service. Citroen in the UK will be happy to charge you around £250 or over! However, you can probably get this for a great price from a breakers yard - and I did see the correct Berlingo with tailgate that has this spoiler on a web breakers yard site last week.
The 8742Y8 bracket part has a weather strip around each of the protruding plastic guide prongs (5 of them) and around the bolt holes (another 5 of those). I am somewhat put off having to drill lots of holes into my tailgate. I thought about whether this could be fitted, as other OEM manufactures sometimes do, with 3M automotive double sided sticky strips or adhesive/sealant like Sikaflex 221. But this spoiler arrangement is pretty much placed onto the back side and on a vertical drop, and has the weight of two parts - the central part of the spoiler sticking quite far out too and at 90 degrees. For me it had to be bolted on to the tailgate - gulp, time to get the drill.
1) First snip off the 5 plastic guide prongs on the bracket. I used pliers to rip them out and it left a little bit of stump, so had to ground it down further with a file.
2) Your bracket is now the template so place it onto the tailgate and mark where the 5 bolt holes are on the tailgate. Best done with two people, at the least to reassure you the spoiler in the right position to mark properly the hole positions.
3) Next drill holes in your pride and joy! I personally went with masking tape over the area in question, made a tiny starter dent/hole punch type thing using an old screwdriver with a couple of hammer taps, then start to drill into that starter dent until the drill bit went through the outer tailgate skin (the Berlingo tailgate is double skinned).
4) I'm using jack nuts. Why? because wasn't keen on drilling from the inside of the tailgate to make a hole big enough in the second skin to connect nuts to the bolts coming in from the outside. Jack nuts can be useful when you have no access to the other side of a thin wall. Before inserting the jack nuts in the hole I prepped the hole with some de-burring/filing around the edge. Weather /water sealing around it using a sealant adhesive from Halfords, and then before the gel like substance is set I insert the jack nuts. The way they are set means they give a very solid nut for the bolt that screws the spoiler into the tailgate.
5) Now place the spoiler bracket into position on the tailgate and screw the bolts in. I tightened them in a bit at a time evenly. Once in solid the outer top spoiler section goes in on the bracket. The top is very tightly secured to the bracket part once it is clicked shut into position.
6) Pat yorself on the back