Differential gear oil question

[goingcrazy2fix]

I have 95 gmc c1500 4.3l 2 door standard cab - vin "Z"

RPO code in glove box shows -> GU6 = 3.42 ratio.

FLUID LEVELS ?????

Amsoil shows the following for

Differential, With 10.5 RingGear With D Rear..........5.5 pints
Differential, With 10.5 RingGear W/O Rear..........7.2 pints
Differential, With 12 RingGear Rockwe Rear..........13.9 pints
Differential, With 8.5, 8.625 R Rear..........4.2 pints
Differential, With 9.5 RingGear Rear..........5.5 pints
Differential, With 9.75 RingGear Rear..........5.5 pints

between 4.2 qts and 13.9 qts ??????

Ratio and ring gear ???? GU6 tells me nothing.

Questions :

1.) Any ide of how much gear oil I need to buy in advance ?
2.) Is Lucas # 10047 is 75w-90 full syn the right stuff ?

 

[ktownloudog]

Well there are two pints to a quart. So if you buy it by the quart you only need to buy half the number of pints it calls for. But call you dealer parts department and have them decode it for you and tell you which diff you have. I'm willing to bet you'll only need 5.5 pints, so 2.25 quarts. You can't buy .25 quarts so you'll have to buy 3 quarts.

 

[Parts007]

Being a c1500, you probably have the 8.5. Unless you have so heavy duty option (rare), which would give you the 9.5

Put up a VIN or message me, I will try to decode.