Where to get 4L80
They are hard to find.
The prices I got while looking for one were $400 for one not guaranteed rebuildable,
$500 to $600 for a guaranteed rebuildable core. $800 to $1000 for one out of a vehicle in a junkyard, $1800 and up for a rebuild.
They come in some 3/4 ton and most one ton trucks and vans from '91 and up.
Avoid the '91 and '92 years. Shoot for a '97 and up.
Some bigger trucks have parking brakes on the tailhousing. If you find one of these you can convert it to work in a car with a regular tailhousing and a th400 type slip yoke.
I got more info if you need it.

