Awd Models?

I Dont Own An Astro But Thinking Of Buying A Used Astro Awd In The Near Future. Does The Astro Offer A Manual Or Push-button Awd Transfer Case, Or Is The Transfer Case Always In Awd? If It Is Offered, What Year Models? I Appreciate Any Help.

I own a AWD Safari. There's no button to select 2 or 4 wheel drive on the Safari/Astro. The front wheel drive only engages when the rear wheels are slipping. There's a few speed sensors, in the transfer case, that measure the difference in speed between the rear wheels and the front wheels, and front wheel drive is selected if the rear wheels are slipping.

Yves.

Thankyou for your help. I really appreciate you explaining the AWD system to me. I still have another confusing question for you. I was looking at this web-site & it gives a year-to-year review of the astro. well in 1999 it states:

1999 Chevrolet Astro: Astro's all-wheel-drive system was revised so that power was only sent to the front wheels when needed for maximum traction. Other changes included a standard overhead console on LS and LT trimmed models.

this seems to be the same awd system you explained to me. i was wondering how the system worked before 1999? do all wheels pull at once? the review page didnt explain this. can you help me with this? thanks.

They have a viscous clutch in the transfer case that divides up the power to front or rear as to where needed.
They are a all wheel drive/full time 4 wheel.
MT