i've seen them advertised numerous times. but i've never seen any in person. last set i had were 3.5 backspacing. i've had prostars with 4.5 b/s. i guess i want 4.5 backspacing then if 4" isn't available.
have a really really nice set w/ (i think) 3.5 BS if you wanna take that route. comes with like new front tires, and nitto DRs on the rears with some life left.
15x8 rear, 15x7 fronts. http://www.turbobuick.com/forums/parts-sale/311504-draglites-fs-ft-mint.html
price is way negotiable, 850 was just a starting point.