You can, there are some important factors of doing this specific job though.
To remove the seal really is not a big deal. Unbolt the rear of the drive shaft from the rear end. Then remove the large nut inside the pinion yoke of the rear end. At this point, the pinion flange either comes off with no issues or can be hard to remove. They do have a puller for this purpose.
You can also use some heavy brass to hit it from the back side and that normally works to break it loose. Remove the defective seal.
Install the new seal, slide the pinion flange back in and bolt it back in place. This is where there can be issues. Officially,,,, you should replace the crush sleeve, but often you can get away with not replacing it. If not, find the proper torque spec to tighten the nut to and do so using a torque wrench. Then put the drive shaft back together, fill the rear end, put the plug back in and go for a test drive...
Technically, there is more to it than what I described as the nut is what puts a pre-load on the pinion which has to have a fairly specific clearance with the ring gear which operates the spiders and the axles. All of these clearances are important to prevent early or aggressive wear on the gears.
Here is a link of doing it the "easy" or "basic" way..