Axle code

[custom63]

Hey everyone.
Im looking to pick up a replacement rearend to upgrade my rear axles to 5x5. I have a line in a '72 1/2 ton rearend but I am unsure of the ratio. The seller said that the axle tube serial code reads thtwo191. Does anybody know what that says about it????? I really need to figure out what the ratio is. I am hopeing to figure it out this way before I drive out and check it out and possibly pop the cover. I wunna know what I have and what I am talkin about before I pull out the cash.

Thanks any and all help.

[rideblue00]

I have a book that is called "Chevy truck I.D. numbers" 1946-1972 Based on the code you list my book says its a 1971 3.07 Do not know if its posi or not. There is supposed to be a +- which equals "No Positraction" Im not clear on that tho. I am going to attach a pic of my page its on.

[taclem]

Is there anywhere else I can get the numbers mentioned above? When I bought my truck it was a '66 long fleet, C10, and I got a short wb frame and also a 292 & 4-spd, nothing is known as to what year any of them other than my cab and front clip are. Thanks, taclem

[custom63]

Thanks for the info. They guy said it was out of a '72 though. Could the codes be different for a '72?

[custom63]

On your frame there should be a VIN number stamped into it. It should be on the top rail of the frame near the steering box. Is that what you were asking?

[taclem]

no, the frame that is under it now I need to decode so I may find the rear ratio, it must be one of the lower ones because I sure could use another gear. The original frame I still have the back half for a trailer. What I am thinking is that maybe I could swap out the rear ends if the original rear end is from an automatic which should be a higher ratio. I just tried to ID the original vin number and the source I was using said it was a suburban, not hardly.
Thanks again, taclem

[custom63]

Does anybody have any other thoughts on my axle question?

[steverino66]

Originally Posted by custom63

Does anybody have any other thoughts on my axle question?

Anything is possible on these old trucks - my 66 has a Frankenstein sort of 64 rear end housing with a GM posi unit from a 71 C10, new 3.42 gears and CPP 5-lug axles!
I'd pull the rear cover to be sure of what's in there.

[custom63]

I also have an axle tube code for a 1971 Chevy 1/2 ton van. Which is TPJWO56. Anybody know any info on this one? BTW do the Van rearends differ from that of the truck ones. Like widths and brakes etc. Im looking to put this under my '63 for a 5x5 swap. Ive thought about just redrilling my current axles or buying the $500 axle kit from CPP. But I also have a limited amount of funds with still alot to do to my truck. So Im looking for the best option for the money.

Thanks again guys, This site is great.

[rideblue00]

TPJ 3.07 shows for 1970 C10 pickup.The codes are different every year. TACLEM: you need the numbers off the axle. Frame numbers wont tell you.

[rideblue00]

BTW, do the axle swap if its in good working order and its from another trailing arm setup. I dont have any info on the width of these axles. I have read on this forum that the 67-72 axles are 1 inch or so wider. 73-87 years are wider still. I also agree with steverino on taking the cover off to be sure of axle ratio and posi status. as far as redrilling axles go thats fine just make sure you find a drum that fits. Im not sure about redrilling drums. I suppose you can if you have life left in them. Most people use a newer 5 lug drum. But be aware of the new drum center hole size. It will need to match the axle boss.

[custom63]

Both these axles are from a spring setup so I would have to weld new perches, so it would not be a direct bolt in. Ive heard of the redrill process just unsure of it. Gotta find a shop that knows what they are doing. I am also unsure of what ratio I want. My current 6 lug on my '63 is a 3:73 non posi and I am pretty sure the two rearends Im looking at are 3:07. My current engine is a IL250 with a TH350 tranny but I may or may not be changing that, budget will decide that one. Thoughts? BTW the rearends for sale are priced at $40 for the 1970 Van one but its a 2 hr drive away and $100 for the 1972 truck one thats only 30 min away. Both are fully complete drum to drum.

[fleetsidelarry]

custom, is it a '71 Van or a '70 Van (you said '71 earlier and '70 just above) '70 would be 6 lug, '71 would be 5 lug. shouldn't be any difference in width from van to pickup but they'll both be 1.5 inches wider than what you have now. you have leaf springs now or coils?(you said both the axels were from 'spring' setups but didn't state whether they were coil or leaf. starting in '73 the rears are leaf which might make the swap easier is you currently have leafs

[custom63]

Originally Posted by fleetsidelarry

custom, is it a '71 Van or a '70 Van (you said '71 earlier and '70 just above) '70 would be 6 lug, '71 would be 5 lug. shouldn't be any difference in width from van to pickup but they'll both be 1.5 inches wider than what you have now. you have leaf springs now or coils?(you said both the axels were from 'spring' setups but didn't state whether they were coil or leaf. starting in '73 the rears are leaf which might make the swap easier is you currently have leafs

Good catch Larry. Its been a long day. Anyways, it is a '71 Van 5 lug and a '72 truck 5 lug both half tons. Both the rearends are setup for leaf springs not coils like my '63 has. If I go with the 3:07 set how much of a dog will she be? I live in an area with kinda alot of hills. I want to pull the trigger on something. Either it be one of these rearend or look into redrilling the axles and turning down the center hubs and matching them up with a later model drum or I have also found an axle kit through ECE to setup on my '63's current rearend that has a 3:73 gear set. Its not bad for $319 but the thing I noticed was that it does not say anything about a spider gear set and I was under the impression that you have to also change out your spider gear set on the '63 and 64 year rearend cuz they are a 17 spine setup and your upgrading to 30 spines with the kit. Has anybody on here used one of these setups on a 63 or 63 truck??

[Rich 5150 69]

Originally Posted by custom63

Good catch Larry. Its been a long day. Anyways, it is a '71 Van 5 lug and a '72 truck 5 lug both half tons. Both the rearends are setup for leaf springs not coils like my '63 has. If I go with the 3:07 set how much of a dog will she be? I live in an area with kinda alot of hills. I want to pull the trigger on something. Either it be one of these rearend or look into redrilling the axles and turning down the center hubs and matching them up with a later model drum or I have also found an axle kit through ECE to setup on my '63's current rearend that has a 3:73 gear set. Its not bad for $319 but the thing I noticed was that it does not say anything about a spider gear set and I was under the impression that you have to also change out your spider gear set on the '63 and 64 year rearend cuz they are a 17 spine setup and your upgrading to 30 spines with the kit. Has anybody on here used one of these setups on a 63 or 63 truck??

Just a thought your pushing 3,800 lbs with a six, approx 200 hp, with a th 350 and 307 gears, your not gonna burn up the hills in Auburn, I drove a `65 with a 6 and three speed with 342 gears, and was at the bottom of second gear at Eldorado Hill in Cameron park.

[custom63]

Originally Posted by Rich 5150 69

Just a thought your pushing 3,800 lbs with a six, approx 200 hp, with a th 350 and 307 gears, your not gonna burn up the hills in Auburn, I drove a `65 with a 6 and three speed with 342 gears, and was at the bottom of second gear at Eldorado Hill in Cameron park.

So whats your thoughts. Go with the 373 to make the best of the IL6? Or try and pony up some $$$$ with a different drive train?

[LT1 Burb]

The leaf spring rear end must be out of a GMC and it will be 1-1/2" wider than a 60-66 rear end. I would think with your drive line you would want to lean to a 3:08 ratio anyways unless you have a tall tire. It would give you better mileage but performance will suffer a little. The other thing you can do is mark the drum and mark the yoke, turn the drum and make one revolution while you count the revs of the yoke.

[rideblue00]

Based on the codes you provided, they are both 1/2 ton pickup rearends. A 1970 an 71 years. If they are leaf spring rears i feel it would be cheaper to modify those. If you are not going to run a overdrive auto trans or 5 speed overdrive manual trans, then you need a 3.07, or 3.42 rear gears. Or you can stay with 3.73. Everybody gets excited about the RPM's being to high, but that what these trucks were designed with. Mine is a 3/4 ton with 4.56 and 4 speed behind a 292 6cyl. If you only drive it some times, leave it stock. I drive twice a week and its fine. If you want to drive it daily and want to save gas, get a 700r4 with a mechanical speedo hookup. Keep the stock rearend then.

[stealth_weapons]

i was trying to find this information 3 days ago. searched all over the interwebs and came up with zilch. do you have the info for a 63? so when i find the numbers i will alreeady know what they are

[rideblue00]

Find your numbers first. I will look them up in my book.

[stealth_weapons]

i found some. they dont follow the code though. one was GM7 the other was 3817763N

[k1rodeoboater]

I'm gonna follow this thread, I want to convert my rear to 5 lug as well once I convert my fronts to a disc setup. My plan was to have my rear axles welded and redrilled, though the kits from ECE or CPP may be the way to go.

[Captainfab]

If you do have a '63 or '64 12 bolt rear end, you will have to change the side spider gears from the 17 spline to the 30 spline to accomodate the aftermarket axles.

The full size van rear ends are wider than the pickup rear ends. So it will be wider than 63 1/2". I don't remember if the '71 Van will have a truck 12 bolt or a passenger car 12 bolt like the early vans did. The Vans changed right around '71-'72 I believe.