Oh yes, even if you've got a manual.. I'm not sure why there ISNT one.. considering sometimes it is nice to know the limits.. my '88 never had one.. and I was sorly tempted to just get an aftermarket one and stick it in there somewhere.
Mine was the same way without the tach. I just got a cluster unit out of a SportTrac with the white face gauges and tach and swapped it into mine. Everything plugs in the same and you can get one for like 30 or so from a junkyard.