i do not believe that super six is the only place, well if you know the exact piston in the mustang, i am sure you can go find it in the jegs catalog you will just need to know what piston has the exact dimensions, pin location, rings, someone on here once posted something about it awhile back.
Jegs, Summit, etc does not have that piston. Trust me when I say that Super Six, Tom Morana are the only Safe "off the shelf" pistons that you can buy. Any other place at all will not have it. Summit or Jegs probably cannot even get it.
You would have to send custom specs on it.
I'm in the process of getting some JE pistons.
For those that dont know to much outside of the V6 world
Despite the success SSMS is having with their Weisco pistons, other cars/motors have the WORST luck.
JE and CP pistons seem to be the best brand of custom and off the shelf pistons.
Note theres an offset in the wrist pin required for the 4.3L stroker
the 3.8s dont require that. I'am looking into both piston kits
Trust me if you could get pistons from just anywhere chris and I both would be selling "affordable" forged motors.... I just recently got done with a custom order and you would if you knew how much some of this **** cost.
trust me...SSMS isnt badly priced on those pistons at all.
I've asked ROSS, Wiesco, CP, JE, Race all for qoutes on pistons with custom specs....some all ranged from 800-$950 with rings and the wrist pin...just as SSMS sells. and SSMs is like $805 which is very reasonable. even the set I get I dont even know if I'd try to market it because most people dont understand the difference between weisco or ROSS or JE. plus It would market for over SSMS most likely