Quote:
Originally Posted by 65chevysub
Looking over my SPID, I see the code GQ1 Rear Axle-Standard. What gears does the standard axle have? The engine is a 350, and the transmission is a TH400
84 Sierra Heavy Duty Chassis(C6P)
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The c6p trucks often came with 3.42 gears. The only way to know for sure, is to actually check them.
This process is easier with a second person, and takes about 5 minutes.
Place a jack under one side of the rear axle.
Leave the other wheel on the ground.
Put the vehicle in neutral.
Place a chalk mark at the 12-o'clock position on the tire.
Place another chalk mark on the driveshaft.
Have a buddy turn the wheel EXACTLY 20 revolutions.
Count the driveshaft revolutions, to the nearest 1/4 of a turn.
Divide your result by 10. This is your ratio.
Compare this number with the known possible ratios, and pick the one that's the closest(3.08, 3.42, 3.73, 4.11, etc). If you counted accurately, it should be obvious.
For example, if you saw 34 and a quarter revolutions, your ratio would be 3.42
The 20:10 difference is compensating for the differential action. If you have a limited slip, this method won't work, since you won't be able to turn just one wheel. In that case, jack up the entire axle, and turn the whole axle 10 revolutions instead of 20.