an xr3i is basically yes a 1.6 injection, and the gearbox casings are different as you say above but all are ib5 so will fit ur engine with no probs, ur chassis requires a box with a front mount of four holes found on mk3 and 5 escorts, a mk4 escort uses a 'cradle' to support the box and is mounted where the bell housing meets the meat of the box so to say