The F40 suspension option was available on any full size Canadian Pontiac in 1969. It included revised front shocks and an upsized swaybar, from 3/4 to 15/16 size (though the sway bar bushing hole size is listed at 3/4). F40, often referred to as the "HD" suspension, includes revised spring rates front AND rear.
Spring were computer selected during the build but the parts counter book provides the formulas and lookup tables. F40 and Base are listed separately for each weight category, and front and rear springs are broken out separately.
F41 is the "SPECIAL PERFORMANCE FRONT AND REAR SUSPENSION" option, sometimes abbreviated as short as "SPEC PERF". It includes all F40 equipment plus an additional rear sway bar. I wanted to find out what was special and/or unique to the F41 option for my car, so I went through the parts book looking for parts that were tagged as such. Because F41 could only be ordered on cars that already had the very top engine option, the L36 427/390, F41 is exceedingly rare. In fact, I've only seen one 1969 with it - if you've documented another, please email me!
In searching I found a number of cases where the earlier cars (65-66) might have a special part such as a reinforcement plate on the rear upper control arm bracket or a larger stud for the panhard bar. By 1969 this was no longer a separate piece. It was either interegrated into the design, included on all cars, or omitted altogether. But by 1969 is was no longer a special comnponent for F40/F41. This page focuses solely on 1969 and applies to the Chevrolet B-Body (Biscayne, Impala, etc) as well as Canarian Pontiacs (Parisienne, 2+2).
Note that I have been unable to find any differences in panhard bar or it's bushings - those are the same 1965-1970 on all applications, according to the part numbers.
Here is some of what I found.
I believe this is the part that goes inside the control arm so that the sway bar bolts don't crush the control arm.
This one I'm also not entirely sure about, as I don't know what "HD CHASSIS" is really nomenclature for. Presuming the F41 cars got the HD CHASSIS ball joint, they will use 3918840 and 3883595 ball joints.
The rear stabilizer shaft (sway bay) is one of the main components, and hence
only available on F41 cars. The swaybar is 394926. They were still
available from GM as recently as 2000.
The spacer belongs to the swaybar and so is F41-only.
One example of why this is not a perfect science comes in the front sway bar
bushings - they just list the two sizes without any mention of the option
package. For F40 and F41, you want the one with the 7/8 in diameter hole.
The front shock is special; it would appear F41 cars would run 3192971.
And the rear shock is listed as 6197636 but since that number is also used
without F41, it's not "uinique" to F41.