KMC-25 does not have a provision for installing an antenna on it. It does have noise cancelling.
The KMC-26 does have the provision for the antenna. Straight cord, as Hill said, due to their being coaxial cable in there.
KMC-41 was a newer model.
KMC-72 is the latest model.
All are noise cancelling. The newer ones were designed for the newer radios. The KMC-25/26 were from the TK-x90 series, so getting pretty old. I'd also be concerned about the jacket coming apart.
I still have a lot of KMC-41's in use and they've held up well. If the KMC-25 gives you issues, look for the 41 or 72. Make sure you are getting real Kenwood mics, there's a lot of knock-offs on the market.