Good luck- mine all broke off too. All had rusted hourglass shaped down to under 1/4"...all 4 clip nuts broke free and spun inside the frame- the clip nuts are not available.
Russ Owens put up a nice thread on how he handles it:
http://www.lovefords.org/tech/65_frame.htm
finding a donor though might not be easy.
I ended up adapting a set of chevelle urethane mounts to mine, fished bolts up thru the holes, put push-nuts to hold bolts in place...didnt work out too well- the car creaks like an old house on a bumpy road- think the hard urethane pads on the slick POR-15 painted frame might as well be teflon on teflon...Macs or autocrafters now sells replacement rubber, but you will have to save ALL the steel insert parts- most of mine were shot too- frame was a 'little rough' :
<font size=-1>[ This Message was edited by: ford4v429 on 9/18/05 10:11am ]</font>