100 bucks isn't really worth it unless those are the springs that you want. Especially for some used springs from a friend. I would put another 100 and get the exact springs you want if there is something else you were thinking about. Brand new B springs for example are 150 and are made for your car from summit.
Kevin
Actually, B springs were not made for the Mustang. They were made for another car. Most Ford front coil springs will "fit" other cars/trucks. Also, IMHO, they are a HUGE JOKE! The drop is way too much for that spring rate. It's better to cut stock GT springs by ~0.3" and get a drop of ~0.7" and you also get a slightly higher spring rate. You can cut a GT spring to get the same height as a POS B spring, and you also get the slightly higher spring rate by cutting the spring.
BTW: OEM springs do NOT sag!! The isolators wear down. Anyone that tells you that OEM Automotive springs made after ~1980 "sag" should get a clue!
Once again, IMHO, the Mach1 and Bullitt springs are the BEST choice for Stangs on REAL WORLD streets. WHY do you think that the Ford engineers went HIGHER with the Mach1 springs from when they did the Bullitt springs? There's no cost difference. In fact, it COST Ford $$ to spec and stock the Mach1 spring that has just a 1/4" rise over the Bullitt springs.
I put the POS B springs on my car. What a joke! I love my lowered T-Bird. Not too low, and a firm ride. My Stang with B springs felt ricer to me. My FWD '94 Olds Achieva handled better on real world streets, real world rotaries, real world on/off ramps, etc! So, with B springs, I had a Stang that was too low, handled like cr*p (the CG is messed up), and could bottom out the
suspension without trying that hard on the typical POS New England roads. BTW: I have dual adj Tok struts on my Stang. So, don't tell me it was because of a strut rate mismatch.
They may be fine for some people. But, IMHO, that are not a spring to get for better handling or even for the qtr mile! So, then, WHY then use the B springs? If you want a car that is that low (1.5" drop, NOT want incorrect FRPP book says), then go with a spring with a rate of 700-800+. IMHO, even the C springs are marginal with the drop they have.