Model Railroading > Athearn I'm in need of some Truck Screws

Does anyone know off hand of what size of screw Athearn used to screw down the trucks of Athearn HO Scale F units and a RDC unit ?

TIA 
Tom Hirsch Cherry Valley, Ca.

The "blue box" Athearn F units trucks were fastened down with a black plastic snap- on worm gear housing . These are available from Athearn via a dealer with a Horizon account. 

Matching screws is aqn exercise in frustration!!!  I had 40 matching Ortner hoppers, yet two had truck mounting screws on the coupler boxes, on one end only at that!!!  Normally one would not think twice on the switch, but these held the axle up off the box resulting in one truck running on only one axle.  Athearn sent replacements, and, you just know it, they sent the truck mounting screws.  So, I was on a mission to find proper replacements.  Did find some, but it was time consuming.  A very short flat head, probably 2-56 IIRC.  The threads were shorter than the head.l  Ah, the modeling experience.

RR