off topic question about my truck
 

how possible is is to make my truck(91 chevy 1500 4.3) awd like typhoon or cyclone ?

just leave it in 4 hi all the time then you will have allwheel drive or you can get an axle that is a constant 4wd or all time 4wd
for the front

whata bout a awd transfer case from a astro/safari ?

i dont think they would fit right but i havent done it myself to know

yea i heard if i get a axle on my front end a awd transfer case from a chevy or gmc should bolt right up

theretically it should but will it mount to the trans in the factory bolt locations and is yours short shaft trans or long shaft there are alot more factors then just you heard it will
if your serious about doing it i would try to find a typhoon or whatever else you said and build it back up to what it used to be there arent many in the road these days