We bought a 77 bronco 351w c4 dana 20 t case dana 44 front and 9" rear axles. I no this is mustnag board but i always post here.It doesn't want to shift to 3rd untill it warms up. The guy we bought the bronco from said he rebuilt it and the the vacum needed adjusted. I replaced the old cracked line and i didnt help. I dont no that i trust that he rebuilt it. I checked the fluid no sing of mosture but it smells burnt. He said it was from the new clutches brakeing in. I was thinking of just rebuilding it my self never done a c4 or a auto before though i have done 3 manual everyone says autos are easyer?I gess i will do the transfercase as well it has poped out a couple times when you get in a bind.