2004 xl7. Automatic / 4wd
Mechanic swapped rear which fixed clunking but 4wd appears to now not  be synced .
When activated rear tires chirp and bog down like emergency brake was on .

If your truck drives alright in 2WD but not in 4WD.... then maybe the ring and pinion ratio of the new diff installed by your mechanic does not match the ring and pinion ratio of your front (stock?) differential?   If that is the case.... you will be destroying your drive train attempting to drive in 4WD.

Thanks,  I'm leaning towards the wrong rear was installed but I am not clear as to what the correct rear end gear ratio is to obtain a different rear from another salvage yard

they should be 5:125

Thanks,  I read 5:13 somewhere for the 04'
 and 4:30 for 05' with same options.
Do you have a site /resource I could refer to because the salvage yard wants a descript number gor rear to insure it will work?

there should be a post on here that has all gear ratios.

Thank you ,
 Salvage yard is looking for a part number they really don't go by the gear ratio number to look for the rear diff.

Suzuki won't have a part number for the entire diff assembly, they will have a bunch of numbers for all the bits & pieces that together make up the diff.

If you still have access to the diff that was removed, have someone examine the ring & pinion gears - those are what you really need - if they are in good condition, you can have them swapped over to the replacement - this will come at a cost though, because it is a specialist task.

If the gears are damaged, try to count the teeth - ring gear teeth/pinion gear teeth = ratio to be matched.

As another option, can you get a front & rear diff from the same vehicle - that way you'll get a matched pair.

Thanks but that's not an option at this point with the mechanic involved at this juncture,  it's more of a salvage exchange number I need to secure at this point rather than suzuki

IF your original gear set were 5.12... and 4.88 or 4.30 were installed in the rear axle... then your rear wheels would be turned slower than your front wheels which would cause the effect of "dragging" instead of turning at the same time.

I'm with Fordem, count the ring and pinion on the gear set that was removed from your truck and go with those for the replacement gears.  The salvage gears don't need to be disassembled to figure out the correct ratio. 

Just have your mechanic count the number of teeth on the old ring gear, then have the salvage yard send you a diff with the same number of teeth on the newer ring gear.  Problem solved and no part numbers are involved.

Thanks,  That's sounds good. Would salvage take apart to check ?

Another pic of original rear

Around where I live, some yards will pull the parts you want, others allow you to pull the parts you need. 

There are about ten nuts to remove the diff carrier from the axle housing assembly.  Typically the sealant used for the gasket material holds the diff to the axle assembly REALLY well.  I usually loosen all the nuts, then place a large board or block under the nose of the diff and stand on it to break this seal.  Once the seal is partially broken, you can use a screw driver or putty knife to carefully pry completely off.

If your salvage yard doesn't separate the carrier and won't allow you to do it, then they would need to turn the pinion and carefully compare the turns on the axle shafts to determine the gear ratios.

Im gonna see if mechanic will look into that. Here in NYC they'res no pick and pulls like out in rural towns so I'm kind of at their mercy .Thanks for your responses, I'm afraid I know more than some but  was ill advised to use this shop, I needed someone more than a parts swapper