Holley referencing a wide vs narrow frame -help

[May70]

I have a 67 c20 frame looking to do a 2003 6.0/4l80 swap on.

Holley has a kit I found VK090202 I saw however it references a 67-72 'narrow' frame. They have a separate kit for a 63-67 'wide' frame.

Holley cannot tell me the difference or measurements between either. They also couldn't tell me if these kits are compatible with the c20s vs c10s.

Does anyone know how to tell wide vs narrow on a 67 and have measurements to confirm? I've sent a message to Toddoky asking about the kit, when he responds ill also bring this up. Hoping maybe he knows but no response yet.

The kit looked appealing so I don't have to source those parts separately.