Got lucky this weekend in the 4 Corners Area of our Country with an 8.75 with a 489 Center that came off an D100 I believe.....the perches are indeed on top and the axle housing from axle housing flange to axle housing flange is 59 1/8 long.....If I cut out the 3.5" where the perches currently sit - I'm right at an A-body width...(Close to an A-Body width)