My 98 230 is still running like a champ w/180k on it now but the radio is all but shot. The display has long since disappeared relying on my programmed channels. The last time I changed the battery I jumped another 12v battery in the system to keep my codes.

My question is two parts.
If you put in an after market radio you can’t put in any codes into the radio. Other than the radio itself do the codes lock anything else?
I would also like at the least install a new antenna. I have a hidden antenna right now. Where is the easiest location to connect an antenna into the existing antenna? I heard the antenna is hid in the rear window but when I look in the truck under the package shelf I cannot see any antenna connectors or cable.