http://www.type2.com/bartnik/relay.htm

Ultimate Starter Fix--

Yes you can use a Ford generic relay 6 bucks or
use a WR-1 Bosch Kit made for this problem.
10 bucks from all the vendors.
Ask Ken Ive bought three from him....
Simple to install I did it in 6 inches of snow in an hr with the wind
howling--
should take 20 mins on a nice day..

Check the starter primary ..The thick cable that goes from the  starter to the
 pos battery  or (is it the other way around..only kidding)
It takes a beating --usually frayed and dirty...WARNING....Disconnect the
battery or you may weld yourself when you touch ground--

This is such a screwed up ign system bosch makes their own fix..
look at the diagram....from bosch...

Plenty of room to do this without taking out the starter...

Clean everything..electrical connections depend on CLEAN contact
Clean those battery cables too..

c'ya