I know by reading and heeding the information from the manufacturer earlier in this thread. The connectors are the same and it can be installed with the automatic if you so desire, but it doesn't shift very well and could very well damage the trans. But it is all up to you, there is nothing to stop you. If you have the 251A, then it can be used in either. If you have the 251 then put it in an automatic at your own risk.