78-91 are Kingpin style axles
78-79 F250 Snowfighters and select Crewcab trucks
79 F350 (there was no 78 F350 4wd trucks)
These are the most coveted as they have a leaf mounting width of 32", which is the same as a wrangler or Grand waggy. this means they have the largest Short side tube so if your going with Coils and link system this is the best axle to have.
80-91 F350's are identical to the years before except the shortside tube is shorter and the longside tube is longer, making them harder to fit under a truck.
91-98 are Balljoint style axles
99-03ish there were only dana50's I think and they have a weird 8x170mm IIRC metric bolt pattern
04-present are Dana 60's but have unit bearing hubs and the Metric bolt pattern.
Im not entirely positive on the later year stuff, but the early year stuff should be dead on. If anyone sees anything wrong speak up.
