gaerbox issues

[bainsgs]

Car makes a clanking noise which may relate to the gearbox/slip diff. Car has had a refurb recently after not been driven much. Timing belt etc but gearbox not removed just oil changed with one recommended by Honda. The mechanic I use says it could be the slip diff and not sure if a normal gearbox shop could actually do any refurbs. It almost feels as if something is sticking.

Sorry I am not technically minded but would appreciate any feedback. Could it be as simple as the oil?

Thanks in advance

1996 N Plate manual