[Justin Farrar]

I have a 1994 Chevy W/T K1500 it has a 4.3 Vortec and I'm trying to figure out what gear ratio it has. My axle code is faded in the glove compartment and cannot read it. Judging by the cover it looks to be a GM 8.5 axle I have been told that model truck is geared low. It accelerates much different from a typical Z71 chevy with 5.7 it has no issues but accelerates a lot slower it is obviously not made to take off fast so I am assuming it has low gears because it's a W/T have looked everywhere and cannot figure out its gears. Anybody know the typical gear set for a 4x4 W/T truck with 4.3??

 

[kennythewelder]

The RPO codes on the glove box cover (or door) will tell you what gears the truck came with.
Here are the codes for gear ratios
GU4....3.08
GU5....3.23
GU6....3.42
GT4....3.73
GT5....4.10

 

[Justin Farrar]

The RPO codes on the glove box cover (or door) will tell you what gears the truck came with.
Here are the codes for gear ratios
GU4....3.08
GU5....3.23
GU6....3.42
GT4....3.73
GT5....4.10

Thank you for your reply, but as I said before, my sticker in the glove box is faded cannot read anything on it or make out any description so I have no idea how to figure it out besides counting splines on gears, but considering I just changed my rear diff fluid a few months back I'd rather not go that route lol

 

[kennythewelder]

It can be done by jacking up the rear end, so both tires are off the ground, putting the truck in neutral, turning the tires, and counting the revelations of the drive shaft. The tire must be turned 10 times I think. One wheel must be chalked. And there is some math involved. If you look on you tube, there are some videos on this, but keep in mine, that the tire needs to make 10 revelations for thus to be accurate.

 

[kennythewelder]

Here is the video a co worker and I used to find his gear ratio. I turned the tire 10 times, and he counted the drive shaft revolutions. He had 17 and just a hair. so 17x2=34 so he has 342 gears.

 

[Cowboytrukr]

I have a '95 that came with a 4.3. It has 3.73's.

 

[OLEJOE]

I had a '92 with the 4.3 and it was also a WT and it had .308 rear gears. The drivability was not very good to say the least. Had a very good top end speed but acceleration was slow. Was hard to keep a steady speed on rolling hills. It was a very good truck otherwise.

 

[Beachbourbon]

Here is the video a co worker and I used to find his gear ratio. I turned the tire 10 times, and he counted the drive shaft revolutions. He had 17 and just a hair. so 17x2=34 so he has 342 gears.

I think my easy way will be to check my RPO codes. Of course, if I can't trust those due to the prior owner(s), this is a great resource. Thanks for posting.

 

[OLEJOE]

I have a '95 that came with a 4.3. It has 3.73's.[/QUOTED] My Dad had a 4x4 with the 4.3 but not sure what year model. It had 373 gears.

 

[morkartracing]

Thank you for your reply, but as I said before, my sticker in the glove box is faded cannot read anything on it or make out any description so I have no idea how to figure it out besides counting splines on gears, but considering I just changed my rear diff fluid a few months back I'd rather not go that route lol

Lift one tire, block the front stick it in neutral and rotate the tire one revolution….and count how many times the driveshaft rotates