Can you recommend admin interface gem for Ruby on Rails 2.3.18

I have very old website in Ruby on rails 2.3.18 and I want to add admin interface like activeadmin but unable to install activeadmin in my project because of its old rails version (2.3.18) , If anyboday recommend any good admin interface gem or any hack to install activeadmin in rails 2.3.18 then it will be good.