Are 4 wheel drive and 2 wheel drive hot air stoves different?

[Accelo]

Are 4 wheel drive and 2 wheel drive hot air stoves different?
I know the manifolds are but did they change the stoves also?
What is the threaded hole in the top middle of the stove for? Seems only some of some of them have it?

[PbFut]

I don't have ananswer to your question but do have what I think is an original air cleaner from a 72 c20 2wd in reasonably good condition. I do not need it and you are welcome to it if you need it

[Rods]

Yes they are different

2 wheel drives are made for the curved ram horns and 4x4 are made straight

Not sure what you mean about threaded top

There is a sheet metal screw that holds the stove pipe in place on the top of the shield