No... recent Electrum wallets don't use any file extension (ie v2.x etc). The default wallet is called "default_wallet"... any further wallets are given default names like "wallet_1","wallet_2" etc... if you change the name they will be called whatever name you give without a file extension... ie. "MySuperSecretWallet" etc.

If your old file is called wallet.dat then it is likely from either Bitcoin Core or some other altcoin based on the Qt wallets... (dogecoin core, litecoin core etc)