Just in the middle of fitting my stage 1 box . But noticed on my std box the take off for the speedo seems weird. Theres a large round device with 2 wires and a black plug with a nut on the bottom this is fitted to the gearbox speedo thead. then A long block fits onto this with 2 wires and a plug(which was connected).

Do i need the large device fitted? looks like it maybe converts the speedo reading???