I think John is mistakenly thinking about the full size trucks.
The actuator on the Blazers is a vacuum actuator that "pulls"
the diff into engagement, the full size trucks use an electric
actuator that "pushes" the diff into engagement. There was
a change up to the actuator for the full size, but nothing that
I know of for the Blazer style of actuator. If you are getting
4lo, 4hi, and 2hi, but not 4hi-auto....I'd be looking somewhere
else other then the front diff. Are you truly getting all 4 wheels
turning when in 4hi?
It is my understanding that 4Hi and 4 Auto are two different modes. During
the last 4 years of ownership I have used both quite a bit and 4hi feels
much different then 4auto. I dont know the details of the difference. But
when I hit 4 Auto now it goes into 4 Hi and feels like 4 Hi has always felt.
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