Rear gear?

What Differential gears did the 66 pontiac lemans 326 2 spd come with?

There were a few ratios available. It would depend on who ordered the car and it's primary purpose.

The majority I've seen were either 2.92 or 3.08. The ST-300 trans was limited in how much gear would "work". 3.55s in GTO were the "lowest" (highest, numerically) I've seen, but I don't recall ever seeing that in LeMans or Tempest. I have, by no means, seen EVERYTHING, though...(:-

On the left rear portion of the axle housing, there's a two-letter "code". Get that and check "walllaceracing.com" for what that code means. There's always the chance the gears have been changed once in the last 43 years.

Jim

If You ever have to take the rear end cover off (should be a 10-bolt rear end) You can jack up the rear end and put stands under it so it won't roll and block the front wheels then when You have the cover off it will have 2 numbers there on the ring gear,You divide 1 number by the other 2nd number and it will give You the Ratio!Most Tempest/LeMans had the higher highway gears in them as MrPbody mentioned,2:78,2:56 come to mind because it was higher gears and it gave You better gas mileage!

My Wife's 1966 Tempest Custom (Sprint) Convertible had the OHC-6 cylinder 4-bbl engine and it actually had 3:23 gear open rear end,the Over Head Cam Engines had lower gears in them to give it more lower end power and quicker take off.This went into the 1967 LeMans also with the OHC-6 Engines,some had the 2-speed Auto transmissions,others had 3-speed or 4-speed manual transmissions!

In 1967,'68 & '69 the 1st Generation Firebirds could also come with the OHC-6 engine in I believe 2-bbl or the 4-bbl carb and were fast Cars that could beat the small block Chevy's when Racing because they also had lower geared rear ends!