I doubt it's length critical. Your best bet would be a new plug, but you'd have to identify the jack on the AIS unit to get a match. I'm not sure what it would be if not PL-259.
Second choice would be the inline splice with two plugs and a union. With this type of connection, I like to solder both the center conductor as well as the shield to the adapter spool.
At the other end of the spectrum is the way I put a joint in my radar cable. The video coax in the cable is really tiny stuff, and I couldn't find any coaxial connectors. So, I just crimped eyes onto the shield and center conductor of each end and used a terminal strip. I was pleasantly surprised that it worked!