Well, tonight I thought I would give it another try at finding my rear end stamp codes. And wouldn't you believe it, they were right in front of my eyes the whole time. But now I am not sure of my combo setup.

I have:
396 .030 over with XE268H CC (slight cam between 270/280 grind)
M-21 Muncie
12 bolt posi....

Now, what would be acceptable gears for the rear end? I remember in high school spinning the axles and coming up with 4.11/4.10s. But the code on my rear is KF 05 17 E, which I believe would call for 3.55 stock ratio.

Would 3.55 work with my set up or should I stay with a 3.73/4.10 setup? Not going to be a track car, just a cruiser.

Thanks in advance...
Rodeo73

3.55s are good cruising gears IMO.

Hmm, I wonder if I was smoking something back in high school. I just verified that it is a posi, both wheels spin the same direction and I can't spin them seperately.

BUT.... I get 3.5 spins of the drive line for each wheel spin. If I did this right, its a 3.55 right? Not a 4.10 like I thought it was back in high school?

I don't know. I always pulled the cover and counted ring gear teeth.

A big block with a mild cam and used for a cruiser? I'd recommend 3.07.

You might want to mention what size tires you will be running as they will have an overall bearing on what might be best. If they are the stock "height" then I would go with a minimum rear gear of 3.55 with a four speed and mild cam enhancement. If the tires are taller than stock, then a numerically higher gear would probably work better. Keep in mind that four speeds do not normally work well with a very low numerically rear gear.

Just my two pennies worth.

Tire size is going to be stock or right at it.

Just not sure what combo I should have went with. 3.55 and a M20 or M21. If I run 3.73, M20 or M21?

I am not sure what the overall gearing difference of a M20 vs M21 would make. Can you really tell by driving what tranny is in the car?