ok ji so here we go, when we talk about VSS we talk about this thing,
thats a VSS, the right most cog is rotated by tranny movement and it outputs electrical signals which are proportional to the RPM at with it is rotating, so we got electrical signals, now question remains how to move speedo with electrical signals
now thats a normal instrument cluster with a cable driven speedo, pretty normal, right, so how would you turn a sui with electrical system, here is the answer
acha ji tu phir what you are looking with green grips is what is also called VSS cluster unit which takes input from VSS and turns and electrical motor and displays speed, not sure that white part in pic is infact VSS or what eva but it looks like something similar replacing the usual speedo cable port.
now back to your mechanic, what ever the installed in speedo meter that cant be a VSS for sure, coz it will be lacking proper VSS input, better ask the mechanic himself about the alteration. above mentioned pics are all samples of honda and merely used for explanation purpose only