There is a grid, but it isn't displayed. Click on edit, then on the drop-down arrow underneath the 5th icon group (the center control icons). There you can "snap to" a number of things, including the grid.
The second drop-down on the edit menu will allow you to reverse an object in any of the planes.
Another way is to select the center object, click Attributes (A), note its position, then check that both the other objects are off by the same amount- just in different directions.
Ex:
center cube, position 0,0,0
wing 1, position 10,0,0
wing 2, position -10,0,0
That -should- mean the wings are symetical. FYI you can move objects by typing in new locations on this screen as well, so you don't have to leave, adjust, check, repeat.
You can also adjust using the keyobard
Left and Right move on the X axis
Up and Down move on the Z axis
Page up and Page down move on the Y
Holding Shift makes the movements larger, holding Alt makes them smaller, and holding CTRL lets you move the camera with the keyboard.
Phoenix-D