Body replacer 3d model question

[NikhilR]

Hi, I'm making a body replacer.

 

Basically I modified the upper and lower body meshes to make them thinner.

In this process I had to merge these meshes, smooth and then separate them into two meshes (upper body and lower body)

All vertices are aligned properly, yet when my player character goes into sneak mode the meshes seperate a bit. (see picture)

The skinning modifier was applied properly (I'm using 3ds Max)

(is it a weighting issue?)

What do I do to resolve this?

 

Any help appreciated!