I would think the three head flanges and turbo flange would need to be pre-cut.

Make it with a GT2056 flange


Here is a stock T3 flange:

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine