Q: Can I use my iMac mid2007 as a Display Monitor?

I have an  iMac mid2007 and I'd like to use it as a 2nd display monitor with my iMac late 2013.  The store clerk at Microcenter suggested a thunderbolt connector adapter to a 6pin to 9 pin firewire.  I noticed that my iMac mid2007 doesn't support Target Display Mode so I am curious if there's a way I can use the older machine running OS X Yosemite.