Cat. Converter Questions?

[Ironhorse]

First off, I am not very knowledgeable about the cat. systems on vehicles. Wife and I have a '99 4 WD 5.7L Tahoe bought used 4 years ago, had 67K on it then, now has 108K. Outside of a couple issues has been a pretty good truck. Cloth interior, loaded and comfortable to drive. Just recently the "Service Engine Soon" has come on several times. Truck running fine, plenty of power, shifts smooth, all gauges reading good. Took the truck to a mech. friend I have know for years, scanned it and came up with "code PO430 catalytic efficeiency low bank 2" . He suggested replacing the right bank cat. converter. Several people I have talked to said the cat converter needs replacing BUT they don't "just go bad". Was also told DO NOT install a universal single cat. Spend a little more and go with a "direct fit" style for a lot less computer issues on the Tahoe. To my knowledge the plugs, cap and rotor has never been changed. Planned on doing plugs before this came along. Checked with my wife's GM parts man cousin, best he can do is $865 for a GM cat., local parts house can get a Walker direct fit cat. replacement for $420 plus my install costs. What to do? Do I have other problems than the cat. or will that solve my problem? Kansas does not have emissions testing mandate presently but may be coming in future from reading and listening to the news due to south centralo Kansas ozone and air issues. Bad timing since Santa doesn't need this at this time of year. Sorry for the long post but know very little cat. and emmisions stufff and don't want to spend $$ on something that won't fix the problem.