Thank you jhpadjustable! Try as I might I could not find that datasheet. I think I even looked at Datasheetcatalog.com, must have typed it wrong... That is the correct part data as it fits with the rest of the ECL logic on the board and power/ground locations etc. The ones I have appear to be a prior generation or maybe just a slower speed than the datasheet shows. Case closed!
amyk - No pics, sorry. Away on travel right now. It is a narrow cerdip with a shiny steel center cover. Marked "NEC" and with the numbers I included above.