ib5's bolt straight upto a cvh engine as the bell housing bolt pattern is the same, but the drive shafts dont fit because the joint's are different sizes and the mountings are different, they arent a straight fit but if you make mounts and sort out shafts then you can use 1, you may be able to use ib5 joints on rst shafts, thats something i never tried, but you also need to make sure you get an ib5 box with the right starter position to run on a cvh, you need a box from a duratec engined ka for the starter position to be in the right place for a cvh which is at the front at the bottom, endura engined ka's have got the starter at the back and zetec-s engines as in fiesta's and focus's have got the starter position at the front at the top, failing that you can have the bell housing modified as i'v had to have done on 1 of my gearbox's before.

not brilliant pictures and i know its on a zvh engine now but heres 1 of my ib5 box's with a modified bell housing to move the starter to the front to suite a cvh engine