A pic of the movement, clear and in focus, should give definitive info on the movement sub caliber. Yes, there was a "218D" sub caliber, with the "D" indicating date wheel but there was also a "2181" sub caliber with a date wheel. Other sub calibers of the 218 were also produced.
I guess you should give us some info as to why you are asking about repair. Is this a family watch that you wish to put back into operation or just a watch you came across? It is possible to repair/restore just about any Accutron if you wish to invest the money in it. There are two coils which make the tuning fork vibrate. One or both can be inoperative, the watch could be in desperate need of a thorough cleaning, lubrication and adjustment or there could be other things wrong in the gear train. Once upon a time there were many watchmakers trained in Accutron service and Bulova supplied parts. That is no longer the case. There are still many new old stock parts as well as used parts available to repair Accutrons. There are Accutron specialists who charge $150 - $185, plus parts, to repair them. If you inquire into established watchmakers in your area, you may find one trained in Accutron service and still willing to service them at a lower price.