I am new to this forum and I need some help. This is my first chevy truck.

I was wanting to know does anyone know what the RPO codes are that would tell me what rearend I have and what the ratio is? I really don't want to have to pull the cover if I don't have to. So if anyone can tell me what the code is for the posi and if possible how can I tell what posi it is that would be great.
And is there a code for what type of suspension it has as well. I would greatly appreciate all the help I can get from anyone.

 

To find out your ratio you'll need another person or a large mirror.
You need to mark your rear wheel (safely jack truck up and place on jack stands) and mark your drive shaft.
Then have someone turn your rear wheel one complete cycle and as he/she does that you need to count the amount of revolutions your drive shaft makes within the full cycle of the rear wheel.
So if your wheel makes one complete revolution and your drive shaft made 3-3/4 revolutions...you probably have a 3.73.1 rearend.

As for the posi, as you turn a rear wheel watch the other one...if it goes in the same direction you have a posi, if it turns in the opposite direction you have an open diff, if it spins just a little or not at all you have a limited diff....at least I think that's how it goes.