I found the CDX-GT740UI was the last version that Sony included the port for the remote pod. Unfortunately it is obsolete, I did a quick search and could not find one anywhere.
If you search for a Sony that has model number lower then 740 you might be able to find one with the remote pod connection.
Here is a model that I "THINK" has the remote pod connector but it doesn't show a picture of the back.
Sony CDX GT550UI CD Player in Dash Receiver Brand New 027242795983 | eBay
Do some searches and find the same used models and look at the back and compare to what you have.