3.25's are good street gears for a non-overdrive vehicle that can't use tall tires. They were my favorite STREET gear when I had to drive back and forth to college in the mustang... back in the day. 3.55's buzzed the engine more than I liked on the interstate, but were great off the starting line.
And yes, back when you could find them in the junkyard, many V6 mustangs came with 3.55 gears, but few had t-locs. Factory 8" t-locs are HARD to find. However, they do currently offer a real Detroit Locker for them!
Good Luck!
