In response to my post re info about 383 crate engines, the one we were interested in used non-file fit rings and the person who responded suggested using file-fit rings. Pls educate me--whats the difference and is one better than the other and why? Thx! ------------------ 70 Camaro 350 TH350; 2bbl "work in progress"! Stay tuned for updates! Update(s): 3.42 posi finally installed! Look Ma! No interior! Look Ma! rear susp. done, rear drum brake upgrades, Classic shocks installed! Tires/Wheels have arrived! TT2's 16X7, & 16X8 Front susp. work finally done! Redoing front disk brakes w/all new parts! Steering box rebuilt!