All you rear end guys (4 wheeled not 2 legged) out there... I have a 3.42 rear end with limited slip. I want to know if I find a rear end that has the higher 2.73 gears, would it be difficult to sitch it out? I have never dealt with rear end worh before so I don't know if I need special tools even. Should I seek someone out to do this for me? If there is the slightest chance that I might screw things up <at all> I don't want to worry about that. What would it involve and would any other parts be needed to complete the R&R?
Thanks

 

I guessing you want to get 3.73 not 2.73 or am I guessing wrong? Anyways you will need some special tools, such a inch pound Torque wrench to set the pinion bearing / crush sleeve, and a back-lash gauge to set the correct back-lash on the ring gear. If you've never done it before you would be off taking to a shop that will do it for you. Getting the correct shims inplace for the carrier can be a pain some times, because depending on what the back lash is to be set at, that will tell you which shims to use on each side of the carrier. Good luck.

 

if you change out the gears in the rear, youll have to find a 3.73 front axle also. the front is a sealed unit, and the ZR2 axles are built stronger.

 

Dont exactly understand why?? 3.42 is best to have, but..... questions first. I see that it is 4 wheel drive, or am I wrong???

Is this some attempt at saving gas? It wont help, drive a little slower, buy a taller tire, etc.

If its 4 wheel drive, dont bother. Getting a matched set could be more than fun.

On the other hand, taking out the whole setup, axles and all is the easiest way to do the job. Hard and heavy work, but no real technical knowledge needed if the donor rear is a good one. Half inch drive tools, ratchet, breaker bar, sockets and some elbo grease. Of course the purchase of the donor part may be very much more expensive than simply changing the gearing.

If you're not experienced at the job, dont bother to think about simply changing the innards. You may be best off taking the rear out and buying the parts and letting a shop do that part. You can save the labor on the removal and installation of the rear. The job is best done on the bench anyway, no matter what anyone may think, or tell you.

If you happen to locate a complete unit that can be exchanged, you will still want to replace seals and such prior to install. You can do this yourself if carefull and following the book while the rear is still out in front of you. Much easier than fighting with it on the car anyway.

 

He's gotta mean 3.73, as I think the tallest normal option is 3.08. I'm not at all sure most would notice a change from 3.42 to 3.73, as it's a fairly subtle difference. I've got 3.73s and I wish I had 3.08s. Now that you would notice.

 

Nope you guys are all close, but no cigar.....
It is a 2wheel drive, it already has the 3.42 and I want the 2.73 gear ratio. I have a 78 Jimmy van had a 6 cyl with the one piece manifold and I pulled it when it went south. But put in a early 6 with split manifold but it was in no stretch of the imagine a stock 6. even put Rhoades lifters in it. It was a GREAT running motor. The van has a 3 on the tree with a electric split rear end in it. That sucker would do 85 on the freeway and maybe hit 2ooo if it was lucky.
I bought long wheel base chevy van, don't remember all the particulars right now but it had the 2.73 rear end with turbo 350 trans. I had a guy I knew through a closer friend R&R from the Steering column back to the rear end the chevy into the jimmy. When that new 6 got the 350 and the tall rear end it couldn't get out of it own way but I could drop that bitch into 3rd for around town and on the freeeway it sailed. I was very happy with it unti I sold the van to an ex's son... I think I would like to do the same thing to the BLazer. Didn't figure it was anything that I would want to screw around with anymore. Turned wrenches for many years on you would beleive how many different things. I love to turn a wrench but I don't want any room for error on something like this and I haven't done it before. I won't get my experince omn my main ride....
But what about the positraction. Isn't that a separate piece or unit that is in there and it won't affect any change over?
Thanks again guys...

 

OK. So this is for your 2000 Blazer ?

The easy way would be to swap out the entire rear axle, but as I previously posted, I'm pretty sure the tallest option for the late-models was 3.08. No special tools or techniques required, as blazingsadle pointed out, just the time and patience. I've done it. No problems except for an occasional U-bolt nut seizing.

I assume you could order any gear combo you wanted, but swapping out the guts is a much bigger deal as has already been mentioned, as to tools, shims, setting the backlash, etc. If you've never done it, best to take the unit out and let a shop swap out the gears. I've never changed gears myself and I doubt I ever would, as I wouldn't want the thing to go South on me when I'm doing 85 or 90 on a freeway just because I didn't set the tolerances correctly.

 

Here is a list of RPO's from the list i put up here about a week or so ago... I just took a section of what is there to give the idea of how many different ones that there are and what might fit adn be able to be used...
G11 : RATIO, TRANSAXLE FINAL DRIVE 2.56
G31 : SPECIAL REAR SPRING
G32 : REAR SPRINGS
G33 : REAR SPRING, LEFT SIDE
G34 : REAR SPRING, RIGHT SIDE
G44 : AXLE REAR 3.07 RATIO
G50 : SPRING REAR, HEAVY DUTY, VAR 1
G51 : SPRING REAR, HEAVY DUTY, VAR 2
G52 : SPRING, RR, 15000 LBS
G5O : SPRING REAR, HEAVY DUTY, VAR 1
G60 : SPRING REAR, AUXILIARY
G66 : LEVEL CONTROL, MAN, AIR
G67 : LEVEL CONTROL, AUTO, AIR
G69 : LEVEL CONTROL, AUTO, AIR, HD
G72 : AXLE REAR, 2.14 RATIO
G74 : HEAVY DUTY SUSPENSION
G75 : AXLE REAR, 3.62 RATIO
G76 : POSITRACTION REAR
G80 : AXLE POSITRACTION, LIMITED SLIP
G81 : POSITRACTION REAR AXLE
G82 : AXLE REAR, 4.56 RATIO
G84 : AXLE REAR, 4.10 RATIO
G86 : AXLE, REAR, LIMITED-SLIP
G87 : RING GEAR, 8.50 INCH
G89 : RING GEAR, 7.50 INCH
G91 : SPECIAL HIGHWAY REAR AXLE RATIO 3.08
G92 : AXLE REAR RATIO, PERFORMANCE
G94 : AXLE REAR, 3.31 RATIO
G95 : AXLE REAR RATIO, ECONOMY
G96 : AXLE REAR, 3.55 RATIO
G97 : AXLE REAR, 2.73 RATIO
GH0 : AXLE REAR, 3.54 RATIO
GH2 : AXLE REAR, 2.29 RATIO
GH3 : AXLE REAR, 2.77 RATIO
GH4 : AXLE REAR, 2.92 RATIO
GK9 : AXLE REAR, 4.63 RATIO
GL3 : AXLE REAR, 6.17 RATIO
GM1 : AXLE REAR, 2.59 RATIO
GM3 : AXLE REAR, 3.45 RATIO
GM8 : AXLE REAR, 2.56 RATIO
GMC : PLANT CODE PONTIAC, MI, USA
GN9 : AXLE REAR, 4.11 RATIO
GQ1 : AXLE, STD RATIO
GS1 : AXLE REAR, 2.73 RATIO
GS3 : AXLE REAR, 3.73 RATIO
GS4 : AXLE REAR, 3.70 RATIO
GS5 : AXLE REAR, 4.11 RATIO
GS6 : AXLE REAR, 4.56 RATIO
GT1 : AXLE REAR, 2.56 RATIO
GT2 : AXLE REAR, 2.29 RATIO
GT4 : AXLE REAR, 3.73 RATIO (DUP WITH 5 X 1)
GT5 : AXLE REAR, 4.10 RATIO (DUP WITH GT8)
GT7 : AXLE REAR, 3.33 RATIO
GT8 : AXLE REAR, 4.10 RATIO (DUP WITH GT5)
GTY : AXLE, WIDE TRACK
GU1 : AXLE REAR, 2.41 RATIO
GU2 : AXLE REAR, 2.73 RATIO
GU4 : AXLE REAR, 3.08 RATIO
GU5 : AXLE REAR, 3.23 RATIO
GU6 : AXLE REAR, 3.42 RATIO
GV1 : AXLE REAR, 2.73 RATIO
GV2 : AXLE REAR, 5.83 RATIO
GV3 : AXLE REAR, 3.08 RATIO
GV4 : AXLE REAR, 3.36 RATIO
GV5 : AXLE REAR, 3.55 RATIO
GV7 : AXLE REAR, 4.11 RATIO
GV8 : AXLE REAR, 2.72 RATIO
GW2 : AXLE REAR, 2.56 RATIO
GW3 : AXLE REAR, 2.56 RATIO
GW4 : AXLE REAR, 3.31 RATIO
GW5 : AXLE REAR, 2.73 RATIO
GW6 : AXLE REAR, 3.27 RATIO
GW8 : AXLE REAR, 4.10 RATIO
GW9 : AXLE REAR, 2.93 RATIO (DUP WITH GU3)

 

Of course you can special order almost anything from the factory, but good luck trying to find one in a boneyard. You're going to find mostly 3.42s and 3.73s, and if you're lucky, a 3.08.

If you want anything taller than that, you'll likely have to order a new gearset.