Hello @kartik,
If you have to install an older version of a package, just specify it
npm install <package>@<version>
For example: npm install express@3.0.0
You can also add the --save flag to that command to add it to your package.json dependencies, or --save --save-exact flags if you want that exact version specified in your package.json dependencies.
If you're not sure what versions of a package are available, you can use:
npm view <package> versions
Hope it helps!!
Thanks!!