A dimensionally correct cathedral port block and heads you can print and hold. LS1, LS6, 5.3, 6.0 — the engines most swaps actually start with. Mock it on the bench instead of hanging a long block in the bay to check one clearance.The steel mock-up block that does this job sells for $309. The free models are render meshes — not watertight, not to print tolerance, mounting geometry decorative. This one is built to be printed and measured against.What you download STEP — native solid, so you can bolt your own parts to it in Fusion, SolidWorks or Onshape STL — watertight, print-ready Correct deck height, bore spacing, bellhousing pattern, motor mount and accessory locations, cathedral port geometry Sectioned to fit a 256mm bed Instant download at checkout. Nothing ships. What people use it forHeader and manifold design without the engine present · swap fitment before you buy · accessory and steering shaft clearance · CAD reference for a part you're drawing.Licence — Shop UsePrint as many copies as you like for use in your own shop, including on paying customer jobs and in design work you're paid for. You may not share or resell the file itself. Print-and-sell licences available — ask.Drawn by James Goertz, G1Pro. This is the file I draw cathedral port manifolds against.