Bip39 tool github http://www.video-bookmark.com/user/tucanewhmt Even though it utilizes BIP32 technique you'll be able to however import BIP39 seeds into Electrum wallet. Also other than BIp32 There's BIP44 Model which some wallet use for that era of seeds. For words that only have three letters, there is no 4th letter. As https://bookmarkerz.com/story19951091/bip39-last-word-checksum-bip39-generator-secrets-https-cutt-ly-uryc5rw7