I want to replace the rotten manifold on my 81 B21F. Is this interchangeable with later engines or what would be my options? I want to reinstall the preheat hose(I've won that debate in my own mind, thanks) and the heat shield is long gone. Thanks to anyone who can help!

Are you talking about changing the exhaust manifold or the headpipe? And is re-introducing the preheat hose the only reason you want to make this change?

The manifold *and* the headpipe actually. Reintroducing the preheat hose is one reason, the headpipe and o2 sensor is another. Or am I just opening a can of worms? The whole rig is fairly well rotted

I just pulled a manifold off of our dearly departed '81 245DL. It's rusty on the surface, but structurally very sound. If you're interested, give me a yell.

Greg

I asked because the preheat hose on the B21/B23 emanates from the headpipe. If preheat was the only concern you might have been better off finding the apparatus for the older model.
The oxygen sensor is another concern. As you know, it's right at the outlet of the manifold on your B21. On later cars it's further downstream in the headpipe, almost to the cat. Too new a manifold and you won't have a place to install it.
You will only have opened a can of worms if you buy the wrong parts.
--
'80 DL 2 door, '89 DL Wagon

Thanks to all who offered, but I have good access to plenty of replacement parts. B230, anyhoo. I understand the o2 sensor is further down the line on the b230, I did not know the preheat hose came from the downpipe on the b21 as I haven't been able to look at another one besides mine. There is nothing at all on mine. My question still is, are the heads basically the same? Will the manifolds swap out?

My question still is, are the heads basically the same?
Basically, yes.
Will the manifolds swap out?
As far as I know it should bolt right up.
--
'80 DL 2 door, '89 DL Wagon

For what it's worth to you, I'm parting out our 1981 but I also have the new (to us) 1991 in the garage as well. I can compare the two manifolds when I go out there tomorrow and report my findings back to you, but I'm hardly an authority on the matter. Perhaps this will be of some help to you.

Greg

I should have the parts that you are looking for. Let me know by email