I presume this is all a bit moot now but I got this achievement last night. It's on the very last mission. Towards the end you have to eliminate some resistence at the reightstag. The Gate is to the left of the reichtstag (looking at it from the street side) and the truck is parked to the right of the gate. It doesn't show up as a target on the HUD.

OK, since you're directionally challenged, let me clarify this. Fly over the Reichstag. Fly directly south of the Reichstag, approximately 2 blocks. You will then see the Brandenburg gate. It can be identified by 2 light green colored roofs, the color of the Statue of Liberty. Directly west and across the street will be a park. If you find yourself in this park, one road leads East directly to the Reichstag. The other road will be slightly South of this road in the park, and it will lead East in a straight line to the Brandenburg gate. The truck is parked on the north side of the gate, on the ground next to the northern light green roof. Note that both the Reichstag and Brandenburg gate are on the Eastern side of the river.

That should be more than enough information to get you there, it's as detailed of a description as anyone can give. I have no idea what's in the truck or why we need to kill it. Maybe it's loaded with werewolves or ninjas, just kill it anyway.

You have far too much time on your hands.......

Finding that park is the thing to do. You can't find it on it's own easily. That park is the only one with a road going through it, going right up to the arch. I never saw a vehicle, but a rocket hit at the arch took it out.

it is directly 230m south of the Reichstag, those descriptions are increddibly long winded lol

if you are over the reichstag, just look for those two green roofs. they are south of it but at less than a bomb drop away and hit the nearest gate.

Follow a big river until you see a church with a blue dome. Follow it untill you see the Reichstag, and to the left of that is the gate right in front of a forrest. Drop a bomb on the gate untill you get it. If you still can't find it play the last mission on Arcade, head for the Reichstag when it shows on your map. You won't see the vehicle so just drop a bomb or launch a few rockets. This may have to ben on the last mission, as I couldn't do it in a training session or other Berlin missions.

If you still cant find it, I can guide you to it on MP if your on the PS3.