The bolts that securethe water pump to the timing cover are 5/16x18.
See http://totallystainless.net/totally.html for the bolts. Last time I checked, they didn't have the studs. Nice folks, very into cars of all types. They have all kinds of stainless fasteners for almost every car. The prices are very reasonable, less the $8 for the water pump kit without the studs.
The studs are a Motormite item available at your local Advance Discount auto Parts store.
Motormite Water Pump Stud Kits for Ford, Lincoln and Mercury cars and trucks w/3.8L, 4.6L, 5.0L, 5.8L.
For a founding member you arent to bright..The threads are 5/16"x18 that is the thread pitch the bolt size is a 1/2" sorry just venting my anger for not being a founding member even though I have been here a long time