I have a 67 Chevelle big block mostly numbers matching. I am trying to verify the originality or correct rear differential. It is a 12 bolt with the numbers NF 3894939 on the rigt side facing the front of the car with GM stamped on the left. On the rear of the differential in the lower left the numbers B227 (and maybe an "O" can't make it out) appear. Can anyone tell me what I have and if it is original?

Thank you,

67 red

B227 is the date code: February 22 1967
You need to look on the passenger side axle tube facing the front of the car. that number will tell you everything.

http://www.chevellestuff.com/1967/rear_axle.htm

Thanks Jeff and Mike.

Gary D. (67 red)

Checked and I have a 3:73 positrac with metallic brakes, built in Buffalo on March 22. Matches the car build dates. Very cool. Only non-numbers matching components on the car is the bellhousing which I am going to switch in a few weeks with a "correct" 621 bell housing. By the way, how do you do the attachement at the bottom of your email? Would like to add a picture of my car but don't know how. Computer challenged. Great picture of your engine. Awesome. Work bench looks like mine.

Raining in Michigan.

Gary D
67red