[GTB 351]

Hi Claytopia, My comment referred to the post above yours by DaveD XB. Yes, a 5 inch backspace is ideal on a coupe with 10 inch rims and std width diff.
I'm running 17x10.5 inches at the rear with leaf springs, 315/35 tyres and have heaps of room inside and out. My diff is a bit narrower than std because American Racing bought out Coddington and effed up my order even after I confirmed measurements 4 times. After grenading my original diff at Heathcote a bit over 3 years ago I went 35 spline and full floater which in this state [SA] means I can get my car engineered with rims wider than 10 inch. I will be putting 335/35/17 tyres on my car when it gets back on the road next year and don't envisage having any clearance issues.