Rear Differential Casting Number -- How to Decode??
 

Hello,

I've searched here on the forum and also on the interwebs... But there doesn't seem to be any info on how to decode our truck rear axle casting numbers... And also what the casting numbers tell us. Forgive me if the info is here, but again I searched and couldn't find --

Anyway, the casting numbers on my rear axle are as follows --

NF3896888 GM 59


Thanks for the help!! :metal:

Re: Rear Differential Casting Number -- How to Decode??
 

Sounds like a 3.55 from a Chevelle, but hard to say. Are you sure this is out of a truck? Can you find the 3-letter code?

Re: Rear Differential Casting Number -- How to Decode??
 

Well, it's currently on my truck... I believe it is original to the truck

I'll look tomorrow for the 3 letter code.

Just curious as to what the casting # says

Re: Rear Differential Casting Number -- How to Decode??
 

Not much. If you really want to know what gear ratio your truck came with and what sort if any traction device it has, just change the fluid. Chances are the 50 yr old truck needs a fluid change anyhow.

Re: Rear Differential Casting Number -- How to Decode??
 

Bump. Anyone?

Thanks!

Re: Rear Differential Casting Number -- How to Decode??
 

Code is --

RHA W238 2

I believe this is a '72 3.07 rear and is original to the truck

Re: Rear Differential Casting Number -- How to Decode??
 

You would be correct. Here are the ratio charts:

http://67-72chevytrucks.com/vboard/s...d.php?t=578793

LockDoc

Re: Rear Differential Casting Number -- How to Decode??
 

Thanks. Good to know :metal::metal: