Rear end/axle ID...GM late 50's (I think)

I have an axle with the #'s

L203
3725899 GM3

GOOGLE search turned up late 50's/early 60's chevy passenger car. I would like to narrow it down a little more as far as ratio and application. Sorry, I don't have a pic yet. Those are the only #'s on it (and there is no big "P" cast into it for posi)
The bolt pattern is 5 on 4-3/4. It is a 3" axle tube. It came on my (butchered) 53 chevy TRUCK when I bought it. Unbolts from the front. 10 bolts. Yes, the truck it's in originally was a 6 lug with a torque tube. I just need to know what the replacement/new one came out of, in order to do brake work, etc...

Thanks so much,
Tito

 

there was a thread on identifying these rears recently. basically if it is originally a leaf spring rear it is 55-57 chevy. 58-64 chevy were coils. to the best of my knowledge all the other GM's had the 5 0n 5" bolt pattern.

bring the brake parts with you to the parts house. that's what I'd do.

 

with a 4 3/4 bolt pattern it'd have to be a Chevy, but we haven't gotten as far as axle ID numbers on our Tech thread (which is mostly for Pontiac/Olds rearends, but some of the Chevy stuff applies)...I know on the Poncho/Olds rearends if you look at the flat pad on the pumpkin from the front at the 7 o'clock position there should be a number stamped there (not cast, stamped...about 1/4" tall) that designates a gear ratio, I'm not sure if that applies to the Chevy rearends or not...but you could still check it to see if there is a single digit stamped there...there may be other tech threads here for the '50s Chevy rearend identification, see if you can do a search to find any of them...