cobra intake and gt 40 intake

i was wondering ( dumb dumb me ) i heard that you could get a cobra intake to fit up on a 351 w but now that i went to my engine and actually started to take it apar i noticed that the lower intake is signifigantly bigger now i am wondering if the gt 40 5.0 or do i have to look for gt 40 5.8 lower i feel so dumb now i have a hole bunch of intakes lying around. the latest i have purchased is a cobra intake but now that i am looking at the picks i am thinking it s too small!

You will need the GT40 lower for the 351W it's wider. See them on ebay but watch out I think there are some cast iron ones out there, must be a marine thing.

is there a difference between the gt 40 and the lightning for a 351w my block is from 89 i noticed the lightning was made later on in the 90's

The Early Lightnings used a GT40 intake.