Hey!
Easy one (I think): You can use the 74HC4051 as an suffix for the 4051, right? It´s just a high speed version of it draining a little more current, isn´t it?
Reason of asking: All 74HCs are available as samples @ Texas Instruments. 
yes they are the same
and yes they are sample @ ti hehe
:-[
Argh!!
They´re not anymore… but perhaps those 74HC4851 can be used as suffixes… they pretty look the same and are pin-compatible to the 4051.
What´s with those?
If nobody knows, I´ll try them out…
mmm I think you can try them look at the datasheet if you want to be sure that they are compatible with the 4051!