How to attach a Mesh to armature while keeping transform Hey I have a problem basically I have a HumanBody Mesh and I have a bone structure/armature. The armature is one that I used for a lot of animation. 

I used to have a old body-mesh the used to be on this armature but now I want to switch it out for a new body mesh. 
Im trying to attach the body to the armature but the new body is in a different "pose" than the armature. And I can't change the armature's positioning in edit mode because if I do than all the animations. I previous created for it will be messed up and not work.

So to simplify my problem basically when I select the mesh then selected the armature than press Ctrl + p. To parent with Automatic weights I get this picture below all I need the mesh to do is stay in the same place it was before:



I meant (crtl + p)

The arms go upward in instead of staying where they were. I know I can go to edit mode and match the armature up like that but than my animation will be messed up. Is there a why to do it with out changing it in edit mode:
Thats actually pretty simple, your mesh is parented to the armature in its edit mode state, pose mode is meant to pose your model after it has been rigged correctly.

even if you see the skeleton in a T pose you are actually parenting your T pose (with arms stretched out, like a T) to a rig with its arms in 45°.

you can check this by resetting to rest pose, and seeing how your mesh will be intact but the skeleton will still be offset by the same amount.

As this happens then we apply your rotation of the arms 45° in pose mode, thus rotating the arms 45° more.

What you need to do is either adapt the rig or the mesh before parenting. I suggest you reset your transforms in pose mode to properly see the state of your rig, to reset transforms press ALT+G for location, ALT+R rotation and ALT+S scale.