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As discussed in detail last month, there are many situations where a different height carrier case is needed when making a gear ratio change. Included here is a list of carrier breaks for most popular rearends. Many of these have thick or thin ring & pinion sets available to eliminate the need for changing carriers. Rearends with those options available for some ratios are indicated in the chart below. Now you have the chance to memorize them all and impress your friends. There is really no magic formula the original equipment manufactures uses to decide the actual breaking point for each design. It depends on the placement of the carrier case and the pinion centerline, and those are really arbitrary and up to the whim of a design engineer. As mentioned last month, I do NOT recommend ring gear spacers in any situation. Remember that using a thick or thin gear set has no side effects and will be just as strong and hold up just as well as a gear set that is the factory thickness.
AMC
- M35 3.31 & down / 3.55 & up (a.k.a. Dana 35. Some early models used a thin 3.08 that only fits the 3.55 & up case)
- M20 2.73 & down / 3.07 & up
General Motors
- Cast Iron Corvette 3.90 & down / 4.10 & up
- D36 ICA 2.73 & down / 3.07 & up
- D44 ICA 3.73 & down / 3.92 & up
- 55-64 Chevy passenger 3.70 & down / 4.10 & up (some came stock with thin or thick gears)
- 55-62 Chevy 1/2 ton all use same height carrier
- Early Olds Drop-out 3.23 & down / 3.55 & up
- 7.2″ IFS 3.08 & down / 3.23 & up
- 7.5″ 3.08 & down / 3.23 & up
- 7.75″ 2.77 & down / 3.27 & up
- 8.2″ Chevy 2.76 & down / 3.07 & up
- 8.2″ BOP 2.76 & down / 2.94 to 3.23 / 3.31 & up
- 8.25″ IFS all use same height carrier
- 8.5″ 2.56 & down / 2.76 & up
- 9.25″ IFS all use same height carrier
- 9.5″ 14 Bolt all use same height carrier
- 12 Bolt Passenger 2.76 & down / 3.07 to 3.90 / 4.10 & up *
- 12 Bolt Truck 2.73 & down / 2.76 to 3.42 / 3.73 & up
- 10.5″ 14 Bolt 4.11 & down / 4.56 & up
Ford
- Ford does not use any carrier brakes in any of their “corporate” rearends.
Chrysler
- 7.25″ 2.47 & down / 2.76 & up
- 8.25″ 2.45 & down / 2.56 & up
- 8.75″ all use same carrier
- 9.25″ all use same carrier
Dana Spicer
- D27 3.73 & down / 3.92 & up
- D28 3.45 & down / 3.73 & up
- D30 3.54 & down / 3.73 & up
- D44 3.73 & down / 3.92 & up
- D50 all use same height carrier
- D60 4.10 & down / 4.56 & up
- D61 3.31 & down / 3.54 to 4.10 with thick gear / 3.54 to 4.10 with regular gear
- D70-1/2″ & 5/8″ offset 4.10 & down / 4.56 & up
- D70-31/31″ offset 3.42 & down / 3.54 to 4.10 (4.56 & up will NOT fit this housing)
- D80 3.73 & down / 4.10 & up
Toyota
- 7.5″ all use same height carrier
- 7.8″ (a.k.a. 8″) 3.73 & down / 3.90 & up The OEM Toyota gears of 4.88 and numerically higher ratio used a different carrier case or a spacer. Virtually all aftermarket gear sets made for this rear end are a thick version that does not require a spacer.
- V6 all use same height carrier. There is however a housing offset difference in vehicles factory equipped with a 4.88 ratio. Installing aftermarket gears in these vehicles requires changing the drop-out housing to a 4.56 & down design. The carrier case is the same height for both housing and can be interchanged if the appropriate housing is used.
* Thin Available
** Thick Available
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