I used the biggest bolt I could fit through the existing hole in the frame, and made spacers from a Ford alternator spacer to make the F41 bars clear the GP brace on my Malibu wagon.
I have the F41 bars, GP brace, radiator X braces, core support to fender braces, Monte SS bars front and rear on the Malibu, really helped out the car, the KYBs were also a big improvement. Replacing the tired springs would be even better.
The Bonnebu came with the radiator X, F41 bars, core support to fender braces already on it.
I think the differnce in what car got what brace was in large part determined by the market it was being sold to. The chevrolets got almost nothing, Olds got some, Pontiacs got more, and the Buicks got the most, all tempered by option content. The "sportier" the car, the more it got within a given make. Buicks got better stuff because Buick buyers typically wanted a car with little NVH, whereas a Chevy buyer was buying the least expensive make, so they got jack unless they ordered F41 or a performance model. Seem to be a lot of Cutlasses go through the yard with F&R sway bars, though.