When i put in Low 1 and gas it, it goes normal. but if i go down hill in Low 1 the truck rolls like as if its in neutral without trying to bring the RPM's up and i hear some rattling,skipping noise, why? the motor used hold me back in low 1 if i didnt give any gas.... also, i dont know if its because the warmer temperature outside but after driving for 20-30 minutes i hear some noise from under the truck and it increases and decreases with RPM....anyone got any ideas on whats going on? my truck is a 4.3 automatic 4x4 with 62k miles on it.......

i forgot to mention that im not giving any gas when im going down hill when it happens....

 

What transfer case and size tires you got? That's weird cause I got 373s and 33s and I go like 3mph down hills with rpms blaring

 

Sounds like either bad over-run clutches or a broken lugs on the over-run hub in the input sprag.

 

so that means that i have to pull the tranny out?

 

You might want to have a trans shop verify first, but yeah.