Concerning a 1995 Chevrolet S10. I need to know how the lower portion of the shifter is removed from the transmission. It looks like it is a large hes head that may unscrew.

I had a 1984 D50 years ago with a manual transmission. If I remember right, there is a boot covering the lower portion of the shift lever, and the boot was held in place by a frame screwed to the floor. If you remove the screws, and the knob on the shifter, you should be able to lift the boot and frame up off the shifter. Look where the shifter goes into the transmission, and see if there are visible bolts. Make sure these bolts are all there and are tight. (Don't force the bolts tight - make sure the shifter is located in the transmission properly.)
If the bolts are there and are all tight, then you have some problems internally in the selector rod(s) and/or shift forks, and the transmission will have to be removed and disassembled to repair it.

please state if this is amnual transmission ?or automatic

I suspect the computer controls/monitors the auto transmission. I'm not sure the program is universal so you probably have to swap that too. Other than that. The torque converter, bell housing, drive shaft length, shifter linkage would all be issues to look at.

Well if you can find one from like a 4x4 s10 around the same year it will fit

you should see a plug that looks different from the oil drain plug on the transmission pan, or near the bottom, on the side of the transmission.
remove, drain. You refill through the dipstick tube for trans fluid.
If it's a manual trans, there will be another plug higher up on the trans.
this one will be the fill plug.
Also on the manual trans, some people just remove the shifter and add fluid in the large hole up top.
Youtube and google will be your friend here.

There are like 6 bolts around the bell housing that bolt the transmission to the engine. Two transmission lines that need to be removed from the transmission, linkage for shifter, driveshaft, started,(disconect the battery) torque converter bolts and a few other small conections. The main thing is that when you are assembling it that the converter is all the way in the transmission. If not, the transmission will not **** to the engine and you may try to tighten the bolt which will bust the ears off the bellhousing on the transmission. Just don't force anything.

You'll need to remove the starter, the inspection cover, remove the three bolts going thru the flywheel into the torque converter. Disconnect the driveshaft, support the transmission and remove the transmission mount and crossmember. Disconnect the downshift linkage, any electrical plugs, transmission cooling lines and the shifter linkage. Lower the transmission to get access to the 6 bellhousing bolts, becareful that you don't lower it too far, because of the distributor at the back of the engine. Remove the 6 bellhousing bolts and it should be ready to come out.

Do you mean this is the manual transmission? If it will not stay in gear, you are most likely losing your OD. As a temporary fix, rig a bungie cable to hold the shifter in OD while on long drives. While this is counter-productive for the lower gears, seeing as the cord will pull it out of the other gears if rigged properly, it works well for interstate and highway traversing.

The lower shifter boot is attached to the transmission by 3 10mm bolts. You will need to remove to center consoule and the upper shift boot that attaches to the car to be able to remove the lower boot. Then you can replace the lower boot.

Remove the heater hose clamps and the hoses from the engine side of the firewall. From the inside under the dash on the pass. side, remove the lower panel screws and slowly pry the lower cover down and the heater core will slide out of the heater box. Installation is reverse of removal.