I am pretty sure if you order the metz 54 new you get a box that says Metz 54-mz4/4i. I ordered one a year or so ago unless i am remembering wrong this is what is on the box. I have a new metz 54-mz4 coming tomorrow and will let you know. If you order the one with the nikon module, I am pretty certain that you get the 4i version too.
To confirm this i looked at what was on the B&H web site. The title states Metz 54-mz4 and the mfr no is MZ 54240S. If you type this into google and go to the bogen site -- you get the mz4i version.. Thus, I think they are the same.
Some of the AF-1 models were discontinued but not the metz 54-mz4-- as far as I know.
I'm trying to find a Metz Mecablitz 54 MZ-4i (in US) and I'm having no luck. I'd like the i-version for use with Nikon D3/D300 as well as with the SCA 3902 for use on my Hassy H1. Does anyone have one for sale or know where I can get one? Seems like BH, Amazon and the usual places only carry the non-I version and claim it is a discontinued model. Metz in Germany says it's still in current product catalog and to contact Bogen Imaging US. No response from Bogen imaging yet so I figured I'd try here.