You said that you erased the SSD
The SSD will not show as a startup disk, unless you have a boot system installed on the SSD.
If there is nothing installed on the SSD partition, then try booting to your original restore DVD (the 10.5.6 one, I think), run Disk Utility from the Utilities menu. Click on the SSD model number line, and click the partition tab. Click the drop down for Partition Scheme, and choose 1 partition, and click the Apply button. That should then allow your SSD to be used to install 10.5 again.
Serendipity is a lucky guess !