Bought ignition control module for '90 F-150 300/six, fits on distributer. I can reach screws, but can't see the heads to determine what kind of tool it takes. Tried : phillips, Torx, allen, slotted, nothing. Tried taking impression with plumber's putty, seems like it may be a hex head or a mutant 5-sided head, might just be the despair making me hallucinate. I'm afraid to remove the distributer because of the possibility of getting it out of time, beyond my tools and skill sets to re=set it. Any one know what fastener heads Ford was using on this application in '90?

Looks like your in the "special tools required" category.

KD Tools KDT3197 Ford Distributor Socket at BrandsPlace.com

A 5.5 mm hex-head equates to a 7/32" hex-head. Unfortunately, Ford likes those dinky 5.5 mm fasteners--there are several places they use them.

I think GM does too. The blower resistor module, for instance.

I forgot to do the conversion to 7/32.

Thanks KISS and TXGreasemonkey,
That makes sense given the impression I got with the plumber's putty, will try to track one down locally, if not will get one online using the info you provided. Much appreciate your quick response. Will let you know how it goes. Packrat