Flex Fuel questions

[asshanson]

Found some good info at http://www.megamanual.com/flexfuel.htm

Sensor frequency output, 50-150hz linear (0-100% ethanol):

The frequency of the signal indicates the ethanol percentage. The output frequency is linear with respect to the percentage of ethanol content in the fuel. The PCM provides an internal pull-up to five volts on the signal circuit, and the fuel sensor pulls the 5 volts to ground in pulses. The normal range of operating frequency is between 50 and 150 Hertz:
o 50 Hertz indicates 0% ethanol, and
o 150 Hertz indicates 100% ethanol.

Fuel temp doesn't matter to me, but may be useful to some:

The pulse width indicates the fuel temperature. The normal pulse width is between 1 and 5 milliseconds:
o 1 millisecond indicates -40°C (-40°F), and
o 5 milliseconds indicates 125°C (257°F).

The article also specifies part numbers and where to get the sensors for cheap, and from other articles they all seem to have the same basic Hz output:

Initial testing has been done with the GM fuel composition sensor part number #12570260, which is their latest version of the flexible fuel sensor. The list price is somewhere around $500 (!), a few online parts places has these for $360 or so. However, if you do a search on eBay for "flex fuel", there is a sensor from seller Medimars,who is offering brand new GM sensors (number #12568450, for a 2001 S-15 truck) for $50.00 plus shipping. It operates the same as the other part number sensor. This latter number has been discontinued by GM, replaced by the former number for most vehicles.

For those of you who have this working, how did you hook up the sensor, it doesn't look easy to fit into a fuel feed line unless they make an AN adapter for one of these to tap into a line like a pressure gauge would.