FS2 Rear suspension binding

[kyoshogit]

I have a 2nd hand FS2 which I haven't yet raced. (meant to be tomorrow....)

When bought, the rear wishbones were different, - only one had the mounting for an anti-roll bar. Since reading recommendations about mounting the shocks on the rear of the wishbones, I've done so, & replaced the wishbones with LA255.
The left driveshaft is now binding badly....presumably on the diff carrier nut. I've tried filing a bit of the d/shaft making contact,- still no use.

Are these the wrong wishbones for an FS2?