"Now, how'd that go again"?

[fastback4]

I swear this time i'll write it down....I've got a nice set of 2000 3.4 intake manifolds and they are going on my 1997 3.1 block code "M".
Do i need a set of 3.4 gaskets.. or...do i need a 3.1 lower and a 3.4 upper....I swear, last time i ask.......Tom

[3400-95-Modified]

you need a set of 3x00 large port gaskets. 00+ 3100's or any 3400's

People say over and over again that the 3100 small port and 3400 large port lowers don't match up, But I've always used the 3400 gaskets all around and they've worked fine for me.

[IsaacHayes]

I used the small port gasket kit, and then grabbed the 3400 upper kit.

[95Grand-Am]

If you use large port gaskets on small port heads you will have to drill new locating pin holes. You diffenitly need large port uppers anyways.