jonnyslick

how do you know if used gears are the size the person says they are (will they be stamped or anything)? and how do you know if they're still good and not worn out?

randy78045

Personally I would buy new gears...

mcfomco

You can count the teeth on the ring and divide by the number on the pinion to find actual ratio.

Crazyfast50stang

Mine were used, FMS, out of a F-150, they are stamped at the end.

Joel5.0

^^^^ X2...the only way used gears are safe, would be if we were talking about the 9", bought with the carrier assy...bolt-on and go.

PRO50SC

2 sets of used gears in 2 dif cars. No problems. They were stamped as well.

MSU_Aaron

check for teeth for wear, if they are pointy then the pattern was setup wrong.

nitrous_bob

yes, either method, stamped or count the teeth.

also the size of the pinion gear is a dead givaway.

a 4.10 is vey small in dia. where a 2.73 is huge...about the same dia as the ring gear

cjc5.0mustang

most factory gears are stamped what they are. check for wear on teeth of the ring and pinion set.

jonnyslick

ok ... so the story goes that person A bought the mustang from person B. person B install 3.73's 3 or 4 months prior to selling to person A, but as soon as person A bought the car he swap the 3.73's for 4.10's b/c he wanted "more gear". so according to person A the gears only have like 5K miles on them.

but when i'm looking at the wear on the gears what should i look for? (and btw..thanks for all the help)