CV joints?

I took the car to the garage to see what was making the knocking noise on a day in the country (50 mph) but the noise disappeared when city driving (30 mph). the guy at the service desk said come back when the noise comes back. I'm pretty sure its either worn CV joint or differential. I'd like to go out of town again this week, 50 mile 'round trip. I did a test drive on a feeder road last night (50 mph) and could not get the knock. Is worn
CV joints a major concern? Am I likely to be stranded out in the country with a broken down vehicle?

knocking in the RH wheel decelerating on an 89 Ford Festiva. Haynes manual says knock in wheel is worn inner CV joint or spline in differential.
(Says clicking is worn outer CV joint.) I've had the car up on jack stands a couple of times in the past few days since I heard the noise, rotating the axels by hand. No that I really know what I'm doing but the wheels do have some play in them when in gear but not at the differential end when I try rotating the CV dust cover. I don't know how much play the wheels are supposed to have in them when in gear.

I'm out of the work force and no longer commuting. Its a low milage car ,
101 km (60 k miles), and I put less than 3k km (2k miles) on the car per year. Don't drive it in winter. So its not like I have to rush into anything. If its the CV joints I'd like to try putting on rebuilt axels myself. Always nice to be able to take one's time with these things.

I found another diagnostic test for CV joints. It says to drive the car in a tight circle. I tried it yestderday (Sunday) in an empty parking lot.
Never tried it before. I did not know the car would turn in such a small circle. Some noise comming from the joints but not much.

I think part of the diagnostic problem is there are at least 3 kinds of
CV joints in front wheel drive cars. Some makers put one kind on the outboard and another kind on the inboard. Other makers do the opposite. So
I guess worn CV joint noises differ among makes.

No, CV joints are not likely to leave you stranded, at least not for a long time. However, they don't usually make "knocking" sounds, more like a clickity-click when taking tight turns. At least that's how it starts. They can be noisy for a long time, gradually getting worse, until one day you'll put the car in reverse to leave the drive way and it just won't go anywhere. But that can take a very long time.

You'll have to describe the sound better to give an idea of what else it might be. Does it do it when cruising at a steady speed?
Accelerating? Decelerating? Braking? Going over bumps? etc etc.

Good advice, in fact, try rattling around anything you can see.

Your problem could also be tie rod ends, watch them while you try to turn the tire back and forth in your hands, there shouldnt be any play.

It doesn't matter. They all make noise during a turn and the turn doesn't have to be that tight.

If it doesn't make noise during day to day driving then it isn't in dire need of replacement.

patient: doc! it hurts when I do this...
doc: then don't do that.

Seriously, smack around your exhaust, especially where the pipe comes through the rear fascia. I was worying myself only to find it was the exhaust pipe...