I believe those are 1Mx4 FPM modules. 71C4400 is the base of the part number, and the last digit being 0 is probably indicitive of a FPM part. (Static column is +2 of the FPM number) For example a 256K ZIP with part 514256 is an FPM part, and 514258 is an SC part. The 71C puzzles me, though.
Also, the 514400 is a common 1Mx4 FPM part. With the base being that similiar, I'd be about 85-90% certain you have FPM RAM. (70ns access, even ;-) )
[edit] - fixed some wording, a typo, and added:
The 714256 is also a FPM part, so 51 or 71 prefix doesn't seem to matter. I'm still not sure what the C means. It may have something to do with latency.(?)