And the original screws on this 250K miles have me feeling.. Well, you know. M6 seems too big and M5 seems too small. Anyone have a good source/thread recommendation on screw sizes and best practices to get the old rusted ones out w/out damage and ensure no fuel leakage between the fpr and the rail?

They're tiny. M4 maybe. And they're always stuck.

Needle nose vice grips.

Thanks!