Well, without disassembling them I can tell you this. The "ideal" swap is one where you swap both blade and lockbar as a unit. That would be impossible, since the Endura lockbar is roughly 3/4" longer than the Rescue 3's.
As far as swapping just the blades:
The lock well on the Rescue 3 blade appears longer than that on the Endura 4.
There's about 1/16" difference in the center-to-center distance between the blade pivot and lockbar pivot.
There's a bit less than a 1/16" difference in distance between the center of the blade pivot and the top of the handle.
The Endura blade measures roughly 4 3/8" from pivot center to tip, Rescue 3 handle measures roughly 4 1/8" from pivot center to butt, so the Endura blade would stick out a bit when closed, unless shortened.
Any one of those differences would lead me to conclude that it would not work. You'd probably be better off seeing if Boomer52 could make a Rescue 3 (or Stretch 2) style handle for your Endura.