Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - 1968 firebird , highway RPM way to high
View Single Post
  #10 (permalink)  
Old 04-08-2013, 09:06 AM
big gear head's Avatar
big gear head big gear head is online now
High Performance Rear Ends
Last photo:
Join Date: Nov 2009
Location: Central City, KY
Posts: 3,054
Wiki Edits: 0

Thanks: 52
Thanked 1,272 Times in 989 Posts
A 12 bolt housing is a 12 bolt housing. The 2,3 and 4 series comes from the location of the ring gear flange on the differential. A 2 series differential has the flange offset to the left more than a 3 series and a 3 series is offset to the left more than a 4 series. This is to make up for the difference in the diameter of the pinion gear head for 2.56 to 6.xx gears. The car 12 bolt uses a 2 series differential for 2.56 and 2.73 gears, a 3 series for 3.07 to 3.73 gears and a 4 series differential for 3.90 to 6.xx gears. There are special thick 3.90, 4.10, 4.56 and 4.88 gears that are made to fit the 3 series and there is a special thin 3.73 that is made to fit the 4 series.
Reply With Quote
The Following User Says Thank You to big gear head For This Useful Post:
Crosley (04-08-2013)