Ok so i need to rebuild my rear end i have everything i need except the differential itself. oem on my 95 Cobra is obv 28 spline but i only found one 28 spline limited slip diff. is it really a big deal if i stay with a 28 spline to save money or is it worth it to go with the ford trak lok 31 spline and the moser 31 spline axels Second, i wanted to do a trick flow twisted wedge head but theyre pricey, how much of a difference is there between the trick flow twisted wedge and the gt40x turbo swirl head? or is there a better option cheaper than trick flow? wanting to do this in the next few days so input it appreciated.