1964 Thunderbird, 390 FE
I was looking at a guy's build thread (not on Hotrodders) this afternoon. He had a 59 Tbird that he was hopping up, and replaced the 3rd member with a posi unit and 31 spline axle shafts. The old ones he took off (I assume factory) were 26 spline, and they were tapered, smaller at the pumpkin end than the hub end. My question is why manufacture these tapered shafts? The 31 splines he put in are basically round stock with the splines cut at the end. Maybe I'm dumb, but would it not be easier to take round stock and just cut splines into it like those 31s are?