Change from 2:73 to 3:73

[Fits12]

Hello... Very new to forum (today). I want to change gear ratio on diff. I am looking to change to 3:73. Will my housing support change? RPO codes are gq1 and gu2. Will the 3:73 fit or do i have to change housing? I have an 87 r10 scottsdale 305.

 

[highdesertrange]

it's not the housing you have to worry about. it's the carrier. that's probably a 10 bolt in your truck. I am just guessing but I would say yes you will have to change the carrier. I personally wouldn't put that kind of money in a 10 bolt. now maybe you could find a used one and swap them. highdesertranger

 

[Fits12]

Ok...gotcha....would a chunk from a 93 k1500 work? It has 3:73 and has 8.5 ring gear. The 2:73 is worn out and needs replaced.

 

[JDCHEVY5]

I want to do the same thing to my 83 Silverado K10. I have 2.73s and 33" tires. It has no torque. want to change to 3.73s. whats everything I need to buy? (GM 10 bolt rear, dana 44 front)

 

[HotRodPC]

Ok...gotcha....would a chunk from a 93 k1500 work? It has 3:73 and has 8.5 ring gear. The 2:73 is worn out and needs replaced.

Are you talking the carrier and the gears from a 93 K1500 fit? If both are 10 bolts, I do believe it will. I'd just want to confirm there is not an early and late style with a change that would mean it wouldn't but I'm about 98% certain it will so long as it's a 10 bolt.

 

[jetman]

With all due respect to all the experts out there but I have had surprisingly good luck with GM 10 bolt rears over the years. (rhymes)
If you are running lots of HP thru it, granted it will have a short and miserable life. But for general use and normal HP loads, they seem to hold up rather well. Just my 2 cents...

 

[RecklessWOT]

it's not the housing you have to worry about. it's the carrier. that's probably a 10 bolt in your truck. I am just guessing but I would say yes you will have to change the carrier. I personally wouldn't put that kind of money in a 10 bolt. now maybe you could find a used one and swap them. highdesertranger

IME a 10 bolt is a 10 bolt, the rear carrier in my 87 V10 burb is out of a 79 Z28 Camaro. The 3.73s should still bolt in. 10 bolts aren't that strong, I've broken a few over the years but as long as you don't abuse it you should be fine.

I agree with not wanting to put a lot of money into a 10 bolt, but at the same time you shouldn't have to change the carrier, it's just a matter of whether you think it's worth spending the money or not. It is a lot cheaper to just change gears than swap everything out. If you're not going wheeling or towing on a regular basis or doing big burnouts all the time your 10 bolt isn't magically gonna blow on you for no reason. However if you do plan to be a little rough on the truck then as HDR says it would be a good idea to upgrade.

I want to do the same thing to my 83 Silverado K10. I have 2.73s and 33" tires. It has no torque. want to change to 3.73s. whats everything I need to buy? (GM 10 bolt rear, dana 44 front)

Honestly, if you have 33s I would go for 4.10 instead of 3.73. I have 3.73s and 31s, I already feel underpowered. I'm getting 33s when these tires are done (which is probably soon, they're already getting down there) and when that happens I am also switching to 4.10 gears. You'll still be able to drive it with 3.73s sure, but if you want to be able to get out of your own way at all I would suggest getting something a little shorter than 3.73s. They're great for cruising on the highway 2K rpms @ ~70-72mph with the 31s, but they feel a little tall and I'm dreading what even bigger tires will feel like.

 

[HotRodPC]

With all due respect to all the experts out there but I have had surprisingly good luck with GM 10 bolt rears over the years. (rhymes)
If you are running lots of HP thru it, granted it will have a short and miserable life. But for general use and normal HP loads, they seem to hold up rather well. Just my 2 cents...

Very True on all accounts. For OEM use with a few adders, they're just fine up to about 300hp and no dry pavement burn outs.

 

[HotRodPC]

Ohh, and you're going to hear all the ******** about being C Clip rear axles too. In my life I think I've seen 1 square with an axle coming out of it on the highway. Now I've seen many Fords with that problem, but only 1 GM Truck that I can recall.

 

[RecklessWOT]

Ohh, and you're going to hear all the ******** about being C Clip rear axles too. In my life I think I've seen 1 square with an axle coming out of it on the highway. Now I've seen many Fords with that problem, but only 1 GM Truck that I can recall.

Agreed. The only way I could imagine a c clip falling out and causing you to lose an axle would be if that big pin that holds the spiders in place somehow got worn to **** allowing the axle to go in about a half an inch so the clip could fall out. With that pin in there it doesn't allow the axle to move in far enough for the clip to come out, it's nicely recessed into the end of the axle gear. You'd have to have some serious wear or preexisting damage to your diff to allow that to happen

 

[1low4x4]

IME a 10 bolt is a 10 bolt, the rear carrier in my 87 V10 burb is out of a 79 Z28 Camaro. The 3.73s should still bolt in. 10 bolts aren't that strong, I've broken a few over the years but as long as you don't abuse it you should be fine.

I agree with not wanting to put a lot of money into a 10 bolt, but at the same time you shouldn't have to change the carrier, it's just a matter of whether you think it's worth spending the money or not. It is a lot cheaper to just change gears than swap everything out. If you're not going wheeling or towing on a regular basis or doing big burnouts all the time your 10 bolt isn't magically gonna blow on you for no reason. However if you do plan to be a little rough on the truck then as HDR says it would be a good idea to upgrade.




Honestly, if you have 33s I would go for 4.10 instead of 3.73. I have 3.73s and 31s, I already feel underpowered. I'm getting 33s when these tires are done (which is probably soon, they're already getting down there) and when that happens I am also switching to 4.10 gears. You'll still be able to drive it with 3.73s sure, but if you want to be able to get out of your own way at all I would suggest getting something a little shorter than 3.73s. They're great for cruising on the highway 2K rpms @ ~70-72mph with the 31s, but they feel a little tall and I'm dreading what even bigger tires will feel like.

Pretty sure the carrier series matters. I don't think you can just install a 3:73 ring gear on a 2.73 carrier. May be wrong. I know for a fact you can go from 3.73 to 4.10. But not sure about 2.73 to 3.73Need to pull the cover, and get the numbers off the carrier to see what series it is. Or, have to measure the carrier

 

[1low4x4]

Also, 33's and 3.73s have plenty of power. I went from 3.73s to 4.10s with 33" tires and really didn't notice a difference. Wasn't really enough to justify the trouble of doing it. Now I have 35's and 4.10s but the truck still has plenty of acceleration, and I cruise at 75ish in OD and if I floor it, she goes. Don't feel underpowered at all

 

[RecklessWOT]

That could be true I suppose. I've never dealt with gears as tall as 2.73. The Camaro had 3.42s originally before I put my 3.73 ring on it, and I know of people putting super short gears like 4.56s in a truck that came with 3.73s, but I've never dealt with anything taller than that. 3.08s and 2.73s are something I've just never come across personally. So it's possible that in my limited personal experiences I've just never come across one I couldn't swap over.

 

[JDCHEVY5]

IME a 10 bolt is a 10 bolt, the rear carrier in my 87 V10 burb is out of a 79 Z28 Camaro. The 3.73s should still bolt in. 10 bolts aren't that strong, I've broken a few over the years but as long as you don't abuse it you should be fine.

I agree with not wanting to put a lot of money into a 10 bolt, but at the same time you shouldn't have to change the carrier, it's just a matter of whether you think it's worth spending the money or not. It is a lot cheaper to just change gears than swap everything out. If you're not going wheeling or towing on a regular basis or doing big burnouts all the time your 10 bolt isn't magically gonna blow on you for no reason. However if you do plan to be a little rough on the truck then as HDR says it would be a good idea to upgrade.




Honestly, if you have 33s I would go for 4.10 instead of 3.73. I have 3.73s and 31s, I already feel underpowered. I'm getting 33s when these tires are done (which is probably soon, they're already getting down there) and when that happens I am also switching to 4.10 gears. You'll still be able to drive it with 3.73s sure, but if you want to be able to get out of your own way at all I would suggest getting something a little shorter than 3.73s. They're great for cruising on the highway 2K rpms @ ~70-72mph with the 31s, but they feel a little tall and I'm dreading what even bigger tires will feel like.

I plan on driving long distances on the highway every so often. I'd like to be able to do up to 100mph if I can. and doing a little wheeling here and there also. It already does pretty decent with my 2.73s and does pretty good off road already. Just doesn't have much torque

 

[RecklessWOT]

I plan on driving long distances on the highway every so often. I'd like to be able to do up to 100mph if I can. and doing a little wheeling here and there also. It already does pretty decent with my 2.73s and does pretty good off road already. Just doesn't have much torque

Yeah I feel you there. I take my burb out to Colorado from New Hampshire every so often and it handles the highway just fine with the 3.73s. Especially with the 700R4 my gas mileage isn't even so terrible. If that's all you're looking to do then you'll be alright. Lol I've had my truck over 100 several times but with that stock steering shaft it's a little scary at anything over 85-90. But that's besides the point. With my 31s it's pretty much tapped out at 105-110 pushing 4K+ rpms screaming at me, but with 33s and 3.73s you should be alright at those speeds. You'll still eat gas if you plan to do that for extended periods of time but it'll still be capable for sure. I'm assuming you have overdrive? I can go 85-90 for an hour with no worries besides the fuel gauge, bigger tires will only make it cruise more like slightly taller gears. Not what I would go for personally because I can't stand how much of a dog it is acceleration-wise even with the 31s (especially since I tow cars fairly often), but it will still be wayyy better than having 2.73s for sure lol