66 Chevy truck diff ratio? Can't find from VIN?

[ezbtr]

I'm copying my post from Chevytalk, I get so many good and fast answers from you guys though! <br />Hey guys my new to me 66 1/2 ton fleetside Chevy truck has 283/2bbl/powerglide, runs great, but I'm trying to find diff ratio. Is it on diff. tag on diff? Tag over driver door says, "C154" and "6Z178337" I could track all else(where made etc) thru VIN. Also need to get reverse lights, cig lighter and main inst. panel bulb to work, any hints would be great! And yes all wires are now fixed from rat chewing and a bad chop job insatll for trlr. wires. Thanks guys! Heinz

 

[imported_bjs]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

more than likley its a 4:11.but to tell for sure you can pull rear end cover off look for numbers on ring gear divide the two and theres your gear ratio.

 

[Bob_VT]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

Check out this web site for info <br /> http://www.lightruck.com/axle_parts_rings.asp <br /><br />Bob

 

[Friz]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

I had a '65 w/283 and 3 spd. Rear gear was a 3.73:1<br />I replaced it w/a 3.08 for a X country trip.

 

[dolluper]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

Should have a tag on the dif,what size are your rear brakes,2 different sizes for that year 2 different dif's if still stock and hasn't been replaced<br />Codes Here click on year at axles<br /> http://www.americanclassic.com/paint.htm?p1=axles

 

[Kenneth Brown]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

Most GM's do NOT have a tag. The axle tube is "supposed" to be stamped above the pass side next to the carrier. My 66 had 4.11 in it and it came with 6cyl and 3 spd. Pulling the cover is the easiest way to be sure Heinz, afterall the truck is almost 40 years old. Lots can change in that many years.

 

[Hunky Dory]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

Hold one wheel (jack up one side or tighten the brake star).<br /><br />Mark the driveshaft and the free wheel. Turn the wheel ten times while counting the driveshaft revolutions (I know, I can't do it either, have a friend help). Divide by two, divide by 10. <br /><br />The difference numbers are big so you don't have to guess fraction very accurately, just know the possibilities for the axle set. Then the /2 numbers are obvious: 37+=373, 41+=4.11. <br /><br />I don't know the autotrans numbers off hand but I once had one at about 3.30 swapped into an older MT truck. <br /><br />If the setup won't turn, you have Posi. Good! Release the wheel and do it again but don't divide by two.

 

[steamboatwilly]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

I think the reverse light switch is in the steering colunm,under the dash.I think its with-in the safty-switch.

 

[Dreamer1Q]

Re: 66 Chevy truck diff ratio? Can't find from VIN?

On the ring gear there should be a series of numbers. Look for the numbers that are like 40/10, or something like that. You divide one by the other for gear ratio.