To change the whole box you'll need a MK3 Escort one. The MK3 is the only one with the four bolt mounting on front of the gearbox bellhousing. All the others have a crossmember and a bellhousing without the holes for the bolts.

Internals of MK3 Fiesta and MK3 Escort are mostly the same, IB5 was intruduced with Fiesta MK4.