Axle ratio help

[HotRodPC]

Yes

No, he stated 1984. Year 1985 is the 3.73:1

But Keith mentioned that the BJC is a different code. If I understand right Keith is calling it a broadcasst code, not the diff code on the axle tube. No??? Maybe So??? But then he goes a different route and believes it to be a 4.10 using some long form method with this:
Well done, Lego.

Just to flesh it out a bit more: I see C20903 W LT9 with the three speed auto (non overdrive = MX1) so I'd call it 4.10:1.

K

 

[DoubleDingo]

I'm putting my money on it being 4.10. I have an 81 c20, 350/th400/4.10. I bet his is the same, just newer.

 

[Keith Seymore]

But Keith mentioned that the BJC is a different code. If I understand right Keith is calling it a broadcasst code, not the diff code on the axle tube. No??? Maybe So??? But then he goes a different route and believes it to be a 4.10 using some long form method with this:
Well done, Lego.

Just to flesh it out a bit more: I see C20903 W LT9 with the three speed auto (non overdrive = MX1) so I'd call it 4.10:1.

K

Correct. BJC is the broadcast (pick) code, so that the operator knows which part to put on without memorizing the whole 8 digit part number. This is shown on the build sheet that follows the vehicle down the line. Sometimes they use the last two or three digits of the part number; sometimes the use colors (like the bands on the drive shaft). In this case it is stamped on the axle tube and then there would also be a large paper tag on the wheel stud for better visibility in the assembly plant.

The RPO code is GQ1 (Base Axle), or GT5 (4.10) when specified.

My "long form analysis" is from looking at the Powertrain chart in the info packet.

K

 

[Keith Seymore]

So I need to pull the cover and count teeth to find out what it is?

Not to be a nuuuudge, but it's been almost a year since your first post.

How long does it take for you to pull the cover and count teeth?

K

 

[84GMCSierra]

Not to be a nuuuudge, but it's been almost a year since your first post.

How long does it take for you to pull the cover and count teeth?

K

I finally got my truck back after a so called friend sold me a bad engine that blew up and I could save up enough money to get another one. I haven't had my truck for that long so now getting info on it

 

[Ricko1966]

Just put a mark on the tire at 12 Oclock put a mark on the drive shaft where you can see it Roll the truck 1/4 turn of the tire. If the drive shaft stops pretty much in the same spot it's 4.10

 

[Ricko1966]

Just put a mark on the tire at somewhere you can see put a mark on the driveshaft you can see. Roll the truck 1/4 turn of the tire watching your drive shaft mark if it stops pretty much in the same spot it's 4.10 it's a 1 minute check with a piece of chalk.