Hi mru, welcome. You have two possibilities to place the second solid:
- you can set the z-Placement of the second body to the height of the first pad
- you can set the z-AttachmentOffset of the sketch in the second body to the height of the first pad
But there is more to say: You used the tube connection tool, but there is nothing hollow in your objects. So you better use the boolean Fuse.
But you can do even better: By fusing you say that this should be a single solid. So why not create it as such in just one body? If you go that way, then the offset has to be applied to the AttachmentOffset of the second sketch, of course.