Ok I'm goin' to get a set of junkyard 3.42s to replace the 2.73s in my car right now. I am also goin' to get an SLP posi. I keep getting conflicting info. Some say all I need to do is change the gears 'cuz the posi is the 3-series carrier. Other sources say I must change the whole rear end since mine originally had 2-series gears. Who is right? You guys here said just gears and posi so I think your right.

 

OEM 3.42 gears are a series III. They will work with the SLP series III carrier. Basically, OEM gear ratios that are numerically higher then 3.08 are all series III. -Randy

 

But do I have to change out the entire rear end drum to drum? Have 2.73s right now.

 

You do not have to change the entire rear end. Housings and axles are the same for all ratios, within the specific rear ranges. THe SLP carrier will only fit the 89-up axles; and if your car is a 89 or even a 90, you really ought to pull an axle and make sure it's 28 splines before you buy the carrier, or be prepared to buy new axles (used ones are all but impossible to come up with, without buying a whole rear end).

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"So many Mustangs, so little time..."
ICON Motorsports

 

Thank you for finally putting my mind at ease. I have a 91' so I'm sure I have 28-spline axles. I am goin' to the junkyard soon to pick up some gears! With my gears, posi and L35 S10 TQ my car should be much snappier when I get my engine/exhaust mods done. Thanks again guys!

 

MUCH snappier. I run the Zexel with 3.42 gears in my 91 Convertible and it is great.