Flashback was purely Intamin, though it was at the time when B&M was still working under Intamin (before the split into their own company). All Giovanola did for Flashback was manufacture the steel (like they did for many, many other Intamin rides).
BTW, yes SFWoA is the only amusement park with a CCI, B&M, and Intamin coaster. Cedar Point is the park with the most Intamin coasters (3 currently, WT makes 4).
-Nate
*** This post was edited by coasterdude318 on 11/30/2001. ***