67 formula s barracuda 8 3/4 standard or option?

My 67 273 Commando/auto Barracuda with HD suspension, non-S, came with a 7-1/4. I have the window sticker and the broadcast sheet (axle code 608, pinion code 34). My understanding is that HiPo engine 4-speed cars got the 8-3/4. Sure-Grip would be an option on top of that.