why would the e04c tranny hit hard at shifts but remain smooth the rest of the time. did filter change and flush no help.

 

I had the same issue with my 93 e4od. this may sound a little crazy but I actually had to replace two things. the first was the speed sensor in the rearend housing, and the second was the instrument cluster module as soon as they were replaced no more hard shifting. so start there.

 

There are some electrical connections you could check.
On the left side of the trans is a MLPS ,Manual lever position switch, and the connections have a tendency to become corroded. Check and clean them.