I can't remember, but didn't the Thunderbird "sport" model have a larger swaybar too?
However, I thoroughly suggest the rear, I did notice a reduction in the understeer following the swap.
I've also heard this..I know the thunderbird sports in 96/97 had a bit stiffer suspension and I thought I remember the sway bar being one of the differences. Much easier finding a sport thunderbird/cougar in the jy than a super coupe..haven't seen an SC in any yard in probably 3 years.