Hard drive caddy type?

our hard drive malfunctioned and we had to get a technician to replace it with a new one. we hadn't backed up any files so the man told us we could retrieve them if we got a hard drive caddy. he didn't specify which brand is compatible with ours though. I've looked over the internet and found no help with this. our computer is a dell dimension 5150. any ideas on which type / brand of hard drive caddy is compatible with our computer??