The Dana 61 3.07 gears can be used in the Dana 60 by using the 3.54-4.10 differential and removing material from both the ring gear and the differential flange where the ring gear mounts....some even remove material from the bearing flange to move the differential over. Sources for the gears listed below:

FORD REARS

603438-6 F-250 1974-75

603713-5 603714-1 603540-5 603899-1 1976-78 F-250 4X2

603594-19 1975-78 E-250 (VAN)

603925-1 1979 F-250 4X2

603932-7 1979-80 E-250

603946-1,2 1980-81 F-250 SEMI-FLOAT 4X2

605022-10,12 1981-83 E-350 DRW CHASSIS

605039-5 1981-83 F-350 CHASSIS