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1977 4X4 transfer / hi-lo range

Discussion in 'Chevy Trucks' started by 4X4rock, Dec 30, 2004.

  1. 4X4rock

    4X4rock Junior Member
    Messages: 2

    I recently purchased a 77 chevy shortbed 4X4 AT 350. The 4X4 transfer case shifter plate reads: Hi / Hi loc and Lo / Lo loc . there are, what feels like 2 actual shift positions for hi and 2 positions for lo. Is this a positive traction or "locker"feature for the front or rear or both drive trains?
    Thanks for any help! :confused:
  2. Dana80

    Dana80 Junior Member
    Messages: 1

    trans case

    What you have is a new process 203 transfer case. It works like a differential, in the none locked position giving power to the axle with the least amount of resistance. When you put it in hi lock, or low lock, the transfer case has no choice but to give both axles 50% power. From what I've heard you rarely have to lock it in.
  3. Mark Witcher

    Mark Witcher Senior Member
    Messages: 604

    It has a differential in the transfer case. When in the non lock possition it allows you to drive on hard surfaces with out the drive train binding. Its called full time 4X4. These were a good heavy duty system. Most need to have the chain replaced every 100,000 miles or so.
  4. PackRat

    PackRat Member
    from Kansas
    Messages: 47

    Mark beat me to it. The only other thing I don't like, is that they are really heavy. I've seen several TH400 cases, with the back end broken off, because a NP203 was hanging from it. That 2-bolt mount does nothing to counterbalance all that cast iron hanging off the back. Some, not all, I've seen, had an auxiliary support, that bolted to the side, and the frame, with bushings.
    Other than the chain, they are pretty tough to tear up.