On a 4.3L, the tube extends thru the side of the engine block into the oil pan several inches. Extracting that part will be very difficult without access from the oil pan side which calls for removing the oil pan. However, before doing that, I would try getting the old part out.

Since this part probably has been in there since the motor was first built, it is likely seized. For stuck part like this, I have found that applying heat is a big help. All you need is for the area surrounding the tubing to expand just a tiny bit to break the surface contact. For this heating, I usually use a propane torch...but be very careful because the oil pan gasket is very close. Hopefully, you will have something to grab onto from the outside. Once the tube moves, you will be able to pull it out.

Good luck!