So I have a 73 Charger. The car is being "built up" as a daily driver/cruiser. The original 400ci big block is currently being warmed over with an aluminum top end and Holley EFI. 325hp is the target. I know that the 73-74 had major shifts in the suspension/chassis dept. Anyway, I was wanting to, down the road, install a GearVendors unit. Better mpg, easier on the motor, so on. But recently I was speaking to a 74 owner who apparently looked into it and found that the GV is not a relatively easy install in these models. Crap! I've heard of the a518 swap, but that also requires serious trans tunnel mods that I'd like to steer clear of. I've also heard of some kind of 4l60e style transmission, but that seems risky as now I'd be mixing in Chevy stuff. Frankendodge seems foolish. So the stupid question of the day is this: Are there any other good options for an overdrive? Or must I cut into my floor for it?