I am currently in the middle of a gv od unit on a 69 charger 4 speed car. I slotted the crossmember .100 like they said and it still would not fit. I had to clearance the tunnel slightly AND install smaller bolts (3/8”) instead of the 7/16 that are factory in 69 cars. It’s still very close. We may have to do some more clearancing. I had a friend that dropped his crossmember about 1/2” total plus beat the tunnel in on his 70 chevelle . They say don’t drop it that much but his works fine.