Silver top Zetec gearbox options?

Alot of gearboxes will fit the Zetec engine. Whether they will fit into a Fiesta is another matter .

AFAIK the BC5 and IB5 will both fit onto a Silvertop Zetec. The BC gearbox will probably be the easier 'box to fit in terms of getting things installed and not changing anything else. I would be tempted to go with a MkV Escort (or MK3 Fiesta) item after researching whether they will fit without issues (I cannot see why) since they are said to be sturdier than the earlier items and offer more choices with gear ratios from the various cars that came with them.

The IB5 is said to be the superior 'box with better changes but installing it will come with its own set of challenges, including possibly converting the car to take a hydraulic clutch (IIRC they have a concentric slave cylinder) and converting the car to a cable gearchange.

I can say however that my Ka and my Focus changed gears better than any BC 'boxed car I have owned. My RST is on a ZVH (the block is a 1.8 Silver Top block) mated to a MkV Escort gearbox which has been rebuilt at some stage with a short shifter. Whilst it is the best shifting BC box I have driven I still think the IB5s have the sweeter shift .