What years of the CA20 would mate with the top end head of the 200. For instance, would the block and pistons be ok to use off a ?? year Sentra?

This is more a question to be asked seperate, not something to be posted into the CA20E FAQ

since when did the sentra come with a ca20? I would have to say no....I can tell you that the heads are interchangeable between ca's ca18et ca20e and ca18det although it takes work to get the det head to work on the e or et but it's a bit more easy the other way around.

My other question is what exactly are you trying to do?

The heads on most FWD and RWD SOHC CAs will interchange, but you have to be careful... Some FWD heads had the distributor in the back (at #4 cylinder) of the head, where others had it in the side (at #1 cylinder).

Most CA Stanzas had the right head, I know my old Stanza Wagon had the right head (distributor at #1, silver top). I think most of the sedans had the distributor in the back though.

Ok Now to repeat my question when did sentras come with ca's

They didn't. Only E series, GA16, and SR20.

t11 stanza's have ca20es and i think t12's

Ya, both do. The Stanza only got the KA-E on U12 models (89-92).

That's what I thought so why hasn't anybody stated that they don't when asks if the ca head is interchagable with the sentra's