5.3 vortec to l83 turbo manifold

[cian]

i see all these 5.3 vortec headers for a turbo manifold and they are dirt cheap like 85 dollars on ebay, then i go to find a l83 turbo manifold single side and it costs 250 minimum, its the same design and materials but so much more, i was thinking the exhaust ports and the studs were the same so i could use the older 5.3 with my l83

[CamGTP]

The cylinder heads on a Vortec 5.3 are not the same as the EcoTech 5.3

 

You can see how the ports are way different when you google the pictures.

[TheRiver]

Exhaust manifolds on the Ecotec's are also not a solid piece unit like the Vortex were.