I'm looking to replace the front suspension on my 1966 F250. I am going to go with 1979 parts for the disc conversion. New coil springs are listed for 1975 - 79 but can't find any for a 1966. Will the 79 springs work in the 66 with the 79 I-beams? Here are the springs I am looking at.
New CC818 Front Variable Rate Coil Springs - Pair

 

In my experience...it depends. I swapped a '76 crew cab ibeams into mine and the '76 spring were way too tall. But the '65 springs seemed too low. I made 1 1/4" perch spacers for the '65 springs and that's what I am running today. I could have raised the rear to match, but wasn't interested in raising the truck that much. IIRC, and I'm sure to be corrected, there's not much difference between the F250 and F100 front springs, if any.