What parts would be necessary to build a GPS reciever? Where can I buy
them OEM? The signal output from the GPS reciever needs to be NPN or
PNP so the counter that I have can be calibrated from the pulsed
output to measure distance - speed.  Some examples that would work but
are cost prohibitive are http://www.micro-trak.com/vansco.shtml,
www.dickey-john.com/pdf/iSPEED.pdf, 
www.squibbtaylor.com/brochures/squibb/skytrac7hz_a.pdf, 
www.farmscan.net/productsdetails.aspx?  Something like these units is
what I want to build to use on the new equipment that I am developing.
Thanks

You might get some help here:

Electronic Circuits Projects Diagrams Free
http://www.electro-tech-online.com/