DO NOT get an axle out of a ford!
The differential is on the wrong side!
Chevy has a pass. side drop transfer case, so you need a pass side diff.
There is NO Dana 40. You want a Dana 44 front. That will work with mild abuse.
For heavy abuse / big tires, you NEED a Dana 60 front.
Rear you should look for a 14 bolt Semi-floater, better yet...get a 14 bolt Full floater.
They are unbreakable and have many more parts available for them if needed.
You can get an axle out of a dodge if you need a Dana 60 front, but a little modification is needed.
Don't waste your money on anything smaller that a 14 for the rear, you won't save much.
Belong to 2 4x4 clubs.
wheel a 83 GMC 3/4 ton
Had a guy out yesterday with 54" tires on ........& still buried it.