Hi - 1999 Honda CR-V with ~100k miles on it makes a slight thumping noise (not loud) when you start driving from a dead stop. Noise goes away at about 10 mph, if not sooner.

Repair guy says it's the rear differential components (clutch and collar) -- per Honda known service advisory, but after reading up on this, I think that's a separate problem, which we have also experienced for quite some time (e.g. when turning, there's a different noise). Are these one and the same issue? Thoughts? Most importantly -- cost to repair? (Mechanic didn't have quote yet for flow collar kit and differential clutch set. Thanks!