To jump on the truck to enter the tank park, first run up to the truck (Sneek when you get close, so you wont be heard) and then make sure your standing up. Once you are standing, move to the left side of the truck, and hit the forward key, and jump key at the same time.. You should jump into the truck and away it will go
No, 8827Echo, different level though part of the same mission (if my memory serves me). The original poster is talking about when you first sneak in, just after meeting up in the resistance safe house. You're talking about the next level or so down the road.