Need flex plate for '79 turbo

[dmarx]

I currently have a very minor vibration in my engine that I can feel in the steering wheel. I have isolated it to the engine and not the front end/suspension. My first thought is to replace the flex plate, however, several issue have come up. Is the flex plate external or internally balanced? There are 4 listed listed thru NAPA with only one available. How do I tell which is the correct plate? Any help would be greatly appreciated.
Dan
dlmarx@bellsouth.net

 

[dmarx]

Is it the number of round holes and crescents in the plate? If so, how do I tell which fits my engine. By engine serial number?
Thanks to all who reply.
Dan
803-549-2187