I have an 8.5 10 bolt posi with 3.08 gears in my 1972 Skylark. I have a chance to purchase a 1978 10 bolt complete posi rear end out of a 78 Monte Carlo with I believe 2... something gears for a good price. I have 3.42 gears laying around to put into this rear end as a spare. Would it be worth buying this rear end? Do I need a gear spacer to make the 3.42's work, any other thoughts are appreciated. Thanks Tim
78 was the first year for G-body and 7.5" rear. If so, you don't want that rear. You can use the 3.42 gears on a 2 series carrier provided you buy the spacer plate. I believe Jegs and Summit both sell them for $25-30. The two series GM unit will be 410409 and have three large 9 characters on the case. The three series is 410408 and will have four large 8 characters on the case.
Just look at your 8.5" rear now and then look at one from a 78-87 G-body. You can tell by eye the smaller diameter.
unless... Unless it is a GN rear which is 8.5 and will bolt right under the car. If it is take that sucker even if the housing does not fit your car...I will buy it off you. lol seriously I will (housing and axles) I will send a truck. Most likely it is a 7.5 rear. Some one also could have place a rear onder the car that is an 8.5 but has done some remodeling to the perches etc. Check that cover ...if it looks like yours it will probably be a 8.5. big and round 7.5 is round but abit more squared off and smaller in size. Jim
