I am putting a 355 in my 84 z28.Im trying to find out if anyone knows what longs tube headers will fit in the car without any problems. Thank you

 

There are only 2 choices, and both of them create problems. GM specifically designed that tapered "frame" under there just to prevent headers. EPA stuff. Anyway, Hooker makes a set of 1.75"-primaries, but if you're under 400 HP, use Hedman's 1.625"-primaries.

 

Flowtech also makes a set, but they're 1-1/2" primaries and from most reports, not very good quality (the Summit store brand headers are Flowtechs).

The Hedmans are a good choice.

 

I have hedman long tubes on mine PN# 68468. They were a decent fit.