this is not a trivial job, and has considerable safety concerns, and is not a job I would ever send someone to do, who has not already done this job under supervision by someone who is experienced at this type of work. The weight of the motor is only 1 of many safety concerns.
1st, do you have the correct tools to safely remove the battery and if so, then remove the battery, and thoroughly clean the battery compartment and under the compartment of corrosion, properly dispose of the corrosion-debris (should not be allowed to flush into the watershed, and the dust is a breathing hazard) and mark the the cables so you know where they went/go on the motor.
The next question is how are you going to get under the truck, do you have a pit or are you going to put the truck on a lift, or are you going to remove the forks and turn the truck over so it is sitting on its mast? Do you have stands that are rated for the weight of this truck? it's weight even with out the battery is still more than almost any automotive jack stand is rated for.
If you have gotten to this point, and still think you are going to do this job by yourself, come on back and we can discuss the rest of what you will need to consider b4 you start.