there is only 2 gear sets available for the ford dana 80.the 4.62s wich you have and the 5.13s that i have.if you know of others that will fit it please tell me where to find them as i need to get rid of these 5.13s.they are way too low.they were OK with the auto.i was able to cruise 65/70MPH with it,70 was pushing it.now with the 5 speed its screaming bloody murder at 60MPH.i lost 5-10 MPH with the ZF.i think its cuz the ZF came out of a pickup and not another 450.ive driven other trucks that are the same as mine with 5 speeds and they all cruised 65-70MPH with no problems.another friend has an f350 with a c6 that cruises the highway better than my 94 with the ZF.i like the 5speed but i think it was a mistake.