why is everyone talking about buying this 99$ spline for posi rear? if i was to go get an entire rear end from a 3,.42 posi rear ended f body why would i need the spline thing from SPL? wouldnt i just take the rear out and stick the new one end and it would work right?

 

They're talking about (usually) getting a rear end from a 91-92 V6 car (which has a nice gear ratio and is found relatively cheap because if it's undesirability, but no posi) and sticking the takeoff posi into it, making a cheap and easy rearend. That unit is a stock posi unit from fourthgen Z28s. The takeoff unit only works with 28 spline axles though. If you got a 3.42 posi rear and stuck it into you car, that would work fine; no need to buy anything else.