[Someonenameddavid]

T

The nikkormat will ONLY tell it to fire at the correct time.
It wont relay any ttl info, thats why you need to use the EX's in manual mode.
You will need to know subject distance & guide number for the flash in question because the 550/580's have no thyrister to quench the flash.

I would recommend a vivi 283 except it doesn't swivel. Only drawback.

The 283 and 285 both have removable sensors that fit into an extension cord ( which is hot shoe compatible) with the cord pointing towards your subject you can swivel the flash head any way you choose, the vivitar bracket grip does this for you.

David