there are several that will fit but non ive found that are big enough in amperage, the ones that fit are usually 70 or 80 amps, these usually only last 12 months, some of the after market ones advertised as for bongo's are only 80 amp too so be careful when you buy.
the best and original are 90 amp ones, originally with the green band around them.
i think ian at bongo central hq is doing original mazda ones that are reconditioned and guaranteed, give him a shout. or
http://www.bongospares.co.uk/ will sort you a recon or original second user one.