See the first two points "Point Worth Knowing" on the 2nd page of your manual (numbered 41). To use "normal" batteries, you need a different battery holder - accessory 45-39.
Here is an eBay listing for one in South Africa: http://www.ebay.ca/itm/Metz-45-39-AA...item4603e0590b
I don't know whether you could use the NiMH Rechargeable cells in your older flash. I would be careful.