13 word seed phrases where the standard for Electrum 2.0 - 2.6.4:
You should be able to restore your wallet with the 13 seed words by downloading one of the older Electrum versions from the official archives:
Electrum has always kept its backward compatibility when it comes to seed words and things like that. they even keep the short lived features like the versioning for private keys!
in other words unless there is some sort of strange bug uniquely encountered by OP, there should not be any problem with importing old seeds in newest versions. the wallet will recognize them.