How hard will it be to change motors in my truck?

If the motors are the same except for the transmission, you will need to take the torque converter and flywheel off the automatic, take the old manual engine's flywheel and clutch assembly off and bolt it onto the formerly automatic engine. You may need to swap distributors as well, as the advance curves are likely to be different.

Do you have the tools you will need? You will have to have a way to lift the motor out of the truck unless you are stronger that King Kong. If I read your question correctly you are putting a motor that was hooked up to an automatic trans. onto a manual trans. If so you shouldn't have too many problems. You'll have to unhook the exhaust, you should pull the radiator and disconnect everything making sure you tag them so you will know how they go back on. It will probably be a lot of work since this is your first time but if you have an engine crane or strong tree branch and a chain hoist you should be able to do the job. Just take your time and don't force anything. You can do it!

yes it is very simple and if they are the same size engines its even easier, you need to interchange the flywheels so you have to remove the clutch but just put it back the way you removed it thats a good time to check it and replace it if it needs to be,also it will be easier if you bolt the clutch and trans to the engine outside the truck and put it in already assembled.