Ford 9" Question - 31 spline Full Floater or 35 spline Semi Floater??

[darkostoj]

Putting a coilover suspension into my 1968 Mustang from street or track and they offer the kit with an axle housing included.

I Have a brand new aluminum strange 3rd member with a 3.50 gear and S-track differential that is 35 spline. I ordered it for my race car but screwed up and needed 33 spline for that one so I got stuck with it.

I can either order the axle housing as a full floater or a semi floater. If I do the semi floater I can use the 3rd member I already have and save some $$$. If I order the Full Floater it is 31 spline only.

Car is going to be a garage queen with some nice day street miles and a couple fun days at the track a year (have a race car for the competitive stuff)

I'm sure I'm splitting hairs here, but just wanted to get everyone's opinion.

Thanks!