I do not believe anyone has mentioned the speedometer cable support clip on the floor pan support which is done on the passenger side of four speed manual cars. The same clip is used as the one used on the opposite side if the car had an automatic or three speed manual.
I assume you are referring to 379816-S32 as shown (poorly) on the 67 Mustang Chassis Assembly Manual (AM0020) page 25, yiew Y, shown pictorially in "Ford Standard And Utility Parts Catalog, January 1969", page 43, and documented in the library on Mustang Hardware Spreadsheet 67-68. It's also used on 69 thru 73 Mustangs
That one doesn't seem to be a problem - but it appears to be missing from the 68 Chassis Manual (ref AM0025 page 54, view Y). The drawing showing the installation is there, the part number is missing. It will be added to the next release of the Hardware Spreadsheets. I recommend that those with a 68 Mustang and having, and using, a copy of the 68 Chassis Manual add part number 379818-S32 to view Y on page 54.
Jim