Chevrolet Repair: rear diferential, gm rpo codes, axle ratios

Question
what ring and pinon gears came stock in a 1988 K-5 blazer with 5.7L 350

Answer
Hello Eric,
Not ALL 88 K-5 Blazers necessarily came with the same gears.
The way to know what your specific Blazer came with is to look in the glove compartment for the decal with all those three didgit codes are printed on.
Then go to GM RPO code sites, like this one, http://www.angelfire.com/ny2/96transam/rpocodes.html
and go down to the G area, like
GU1 : AXLE REAR, 2.41 RATIO

GU2 : AXLE REAR, 2.73 RATIO

GU4 : AXLE REAR, 3.08 RATIO

GU5 : AXLE REAR, 3.23 RATIO

GU6 : AXLE REAR, 3.42 RATIO

GV2 : AXLE REAR, 5.83 RATIO

GV4 : AXLE REAR, 3.36 RATIO

GV8 : AXLE REAR, 2.72 RATIO

GW4 : AXLE REAR, 3.31 RATIO

GW6 : AXLE REAR, 3.27 RATIO

GW9 : AXLE REAR, 2.93 RATIO
There are many more codes than I coppied. You just need to see what "G" code you have on your decal, and match it up. There are some "F" codes for front axle ratios also.

When you are finished figuring out what your axle ratios are, look up all the other codes also, to see just what you have.

Google search for GM RPO codes, and you can find other, some year and model specific code charts.

Van