Maybe I've got that slightly wrong, and it's the standard Sunny (e.g. 1.6L).
When I last needed some; I bought the ones that Martyn said would fit, plus a set of GTiR ploybushes... and that came-out cheaper than buying "GTiR" specific wishbones with the right bushes already on them. - I didn't notice any issue with the balljoint when I tightened them up, and they've been like that for a while now.
You could try getting the complete wishbones from ADL Bluepriint, always good quality parts mate, the part numbers are ADN18669 (left hand side) and ADN18668 (right hand side), try Camskill or Andrew page motor factors as they are usually better on price, hope that helps buddy.
Rhs and lhs are sold from most motor factors, and yes the differance on new nissan ones is the ball joint on the gtir was a fraction bigger than the gti....it's nothing worth worrying about at all....the rear bush is differant between the two as well....but again just change it.