MIke,
Pic of Ball Joint from the factory circa 1996.... cast body vs stamped temporary steel....! My ball joints self destructed into multiple fragments....sorta like your a-arm bolt/nut affair!!! (That thing musta done all sorts of bad things on the roadways!) Hopefully the shaft will clean up fine!
I need to defer to others and their posts.....whether this be the "big" one or the "small" one (upper(less load) or lower (more load) depending on A-arm/spring design!)......but what you shouldn't need to do.....is grind anything to get things to fit! The balljoint should slip right in place to the a-arm cup!
My crusty brain thinks that the Fiat Mechanic nearby told me..."they were a 124 Joint.....". (Parts book does not give a Fiat number but rather a CAMOZZI name only reference....!)
The tie rod ends are listed as a Fiat 1100 or 1200 or 1300 or 1500 C Dino, or Multipla, or 2300RH..... also as a rear suspension arm thing on an X 1/9. Untouched by DeT! (Not modified!) Original Fiat number # 4100024
Progress!!!
Steve
