I am building one at the moment. Look here:
http://armorama.com/forums/260207&page=1Nice kit. Upper hull fits very well. Parts are detailed and well cast. Any Trumpeter BMP-1/2 or chinese BMP-clone will fit as donor kit. Caution: Trumpeters tracks do not fit well around Trumpeters own drive sprocket.
Be aware that the "mold seam" running criscross the crane boom is a weld beam at the real vehiclo. Do not sand off! You've been warned now! It is recommended to add some more details around the cargo platform. It is missing the locks and handles. That is the only real omission of the conversion kit. Everything else is fine.