dodge uses a piece that bolts to thepedel structure with 4 bolts.

the hole in fire wall is just that. a hole bigger than needed.

master cyl goes in hole then twist locks into the bracket under dash. has a small plastic roll pin to lock it from turning.

a rubber groumet is on the MC and covers/seals the hole in fire wall.

on a truck before hydro clutch there are 4 dimples in the pedal structure but not drilled. and no hole in firewall.

the MC bracket is like a peace of angle bent into a 90* with 4 holes for mounting on 1 side and a large hole with notch for MC to twist lock into.

I have some pics of my hydro clutch 5 speed swap into a 85 chassis. used all bolt on dodge pieces.