Originally Posted by
SB_Greg
It is 8 speed. The only marking other than dura Ace is M5
Here's the obvious link to a compatibility chart.
https://www.sheldonbrown.com/dura-ace.html
Yeah, you're supposed to use Dura Ace RD with Dura Ace shifter in that era. Dura Ace was it's own weird thing. You might be able to use some other derailleur if you hack it with clever tricks to adjust the ratio. Big props if you can get a Simplex to work with them. ( dddd probably has done this already....
)
Personally I'd avoid the hassle and use friction shift and ENE or Silver shifters instead, but I'm used to friction.