Tach generator key way

[Capt.Frank]

I have 3208s and thought I had CAT drives for my tachs but CAT keys are different. I'm having problems identifying the key ways for the tach generator. These things are plastic, not metal. Any ideas??

Here's a few pixs of the part:

[Bruce]

What brand of generator are you using?

[Capt.Frank]

Not sure. This is for a tachometer generator. I changed the tachometers that were CATs (1980's model that had stopped working). I'm installing ISSPROs tachs and I can't get the signal to them.

[Bruce]

Did you buy the generators with the tachs or are the replacements from Cat?

Also what is the ratio of the generator: 2:1, 1:1

[Capt.Frank]

Bruce,
No the generators were on the engines. I did not know untile now that they are not CAT's. I just figured that they were factory tach drives. I have No idea what ratio they are. The tachs (ISSPRO) are compatiable with CAT. The generators look like either a DD or Stewart Warner drives form what pic's I can find. I am thinking about just going to a speedometer shop and seeing if he has any key ways close. The drives work when spun buy screw driver, So I just have to get a key.

Frank