Learn to install vinyl rain gutters with pieces from the old gutter
There are a few pieces you can reuse when you decide to replace the old gutter in your home. Usually most people reuse the downspouts. You can follow these steps for this job.
Remove the downspouts from the gutter by unscrewing the screws which hold it. Be careful how you handle the removing because you may get them damaged and there will be no point in reusing them.
Then after you install the new gutters take the old downspout and attach it there. If you have used rivets to mount the gutter you should probably use rivets for the downspout too.
You need to seal the place where the downspout connects with gutter. Use sealant for this. This way you eliminate any chance of leaking.
If you follow the correct steps and with careful working, you can easily use old parts in the installation process of new ones.