The Stovebolt Site Forums The Shop Area Engine Shop 7 gear 1/2 ton????

anybody clue me up on what gearbox i seem to have
at first i simply thought it to be a 4 speed (chevy 49 1/2 ton swb) but as the trucks not drivable i never checked. scratched on the das panel is a strange gear selection patern 1234h and l? also when moving the floor shift it apears to have reverse left and back then 6 other positions wich is also confirms whats scratched on the dashboard the engine looks like a 216 but has gmc on the v/c
anybody know what im dealing with here??

I think some previous owner robbed a tranny out of a bigger truck...look for a name/data plate on the trans...

ok il check trucks not at home so asap
so would that fit the old il6 lump then??

Sounds like you've got a 4 speed that has a high and a low range -- like on a tractor.

Usually, the trucks that had the high and low range had a two speed axle, and a normal 4 speed. I'm curious as to what you've got, too.

hi brenden not as curious as me! just how do those 2 speed axles work ?how do i tell by looking and is it a good substitute for a 3.23 ratio normal 10 bolt axle?
il go get some more details from the truck asap and post in the meentime anybody any knoledge?

im sure it only has 1 shift stick

Sounds strange to me. BUT, I have actually seen light trucks with a 2 speed rear/tranny gear splitter. The last one I have personally seen was a '41 3/4 ton, never have seen on on a 1/2 ton.

IIRC, the stock 2 speed axle was available only on the 3/4 and up because of the whole torque tube thing.

They were vacuum actuated by a control lever down on the floorboards.

Not sure. I've never looked at one, I just know that they existed (there's instructions on how to pull one apart in my shop manual for the '46). They typically had ratios in the 5.XX:1 to 7.XX:1 ranges (values varied).

It is an excellent substitute for the 3.23 Ratio axle, if you're planning on pulling stumps, hauling hugegantic loads, or changing the rotation of the earth.

If you're planning on driving the speedlimit on the freeway -- not so much.

As I mentioned before I'm not sure what tranny you've got, but it sounds like it acts like a four speed with a 2 speed rear end.

If it has a gmc valve cover, it is probably a gmc motor. Check the pad behind the distributer. the first 3 numbers will give you engine size... 228, 236, 248, 256, 270, or 302. Maybe yours was swapped for a better gmc motor.

Lets see a picture of this transmission.
Are you sure it has 6 positions and a reverse?

Now I see you are from the UK, you could have some sort of transmission swap we are not familiar with over here?

Grigg

hi guys thanks for the input i will go and re check tommorow as best i can without driving it il see if i can drag it out from storage and get a pic or two could be just a mistake but the dash does have the gear pattern scratched onto it suggesting its not commonly known.also its not a uk swap the truck is untouched from leaving usa il check the motor for those numbers also