atf in a transfercase? also rear end and xcase id pls

[67cst]

has anyone ever heard of using atf in a transfer case? my dad just bought a 72 chevy 3/4 ton 4x4 and is just going over everything...he said that the manual says to use atf in certain transfer cases...anyways the code on his xcase is:

1
C-99404
W

the 1 and W are in those places, above the C and below the 9

Also just out curious to the ratio in the rear end, the code off it is:

3934635 i might have a pic of it here if that helps

thanks, Derek

[67cst]

for some reason the xcase code all goes to the left margin, like i said above the w is below the 9...im sure this doesnt make any difference but i just dont want to miss anything

thanks again, Derek

[PICKMUP]

I think our TCs use 90W gear oil. Synthetic might even be better. ATF may have been used in some later model applications.
If you run 90W or equivilent and ATF shows up in your TC, it shows you that the seal went out in your adaptor between trans & TC...a common problem...trans gets low & TC gets over full. Always change that seal if you have one apart.

[Robert1970C20rstbukt]

Where'd you find the numbers on the rear end? I have the same rear end in my truck and I never found the numbers yet. Oh that is one of the Corporate(Eaton) rear ends, Chevrolet used those in trucks from like 47-72.

[4x4Poet]

As long as the 72 still has the original NP205 transfer case, the Chevrolet Service manual states:
TRANSFER CASE: "...Use SAE 'GL-5' gear lubricant, and follow the 'Gear Lubricant Viscosity Table' for proper viscosity gear lubricant to be used during vehicle operation."
REAR AXLES: "...when necessary, refill to level of filler plug hole using 'GL-5' gear lubricant as shown in the 'Gear Lubricant Viscosity Table.'"

So, it's GL-5 all the way. For manual trans too. Now to viscosity:
Gear Lubricant Viscosity Table
Below 10ºF: SAE 80
Up to 100ºF: SAE 90
Above 100ºF consistently: SAE 140

I use Amsoil synthetic GL-5 90W in both my NP205s and in all my pumpkins. In my manual trans, I use Redline's synthetic GL-5 MT90 for the additives they use to make the synchros work not too stiff, not too loose. The axle you pictured looks like an Eaton H052. It probably has 4.11 gears. If you remove the diff cover to change the oil, count the ring & pinion gear teeth and calculate the ratio.

[67cst]

thanks guys

[1969 GMC]

Derek, on both of the Eaton centersections I have, the gear ratio is stamped into them on the side. Its actually the # of teeth on the ring and pinion. 7/36 is stamped on one (5.14) and I forget what the 4.57 one says.

I am guessing 4.11 should be 9/37