Question guys, if I were to, say, want to put my 4x4 transmission into a 2x4 Astro van....would it work? Same motor, same year....

 

Are you wanting to convert the astro into 4wd?

 

if the Astro is All Wheel Drive.
If not you will need to swap the tranny output shaft and install a tailhousing. Basically take the tranny apart.

What are you trying to accomplish?

 

I'm parting my truck out and someone is needing a tranny for their 4.3 Astro.

 

Got it. What year truck and what year Astro?
your tuck 4x4 and is the Astro All Wheel drive?
There are some key years to consider.
2putt8 engine and it wont work.
Assuming both trucks are 4.3, and both have a transfer case.
Then both pre '93, or both '93-'98, or both '98 and newer and your ods increase greatly.
If you cross one of those year boundries it gets more complicated.

If you can keep it to within a year or two the better. There are some differences in the amount of sensors, tranny controls as the years progress.