Hey guys, i'm new with a question about rear ends
 

I have a 1997 grand cherokee laredo and i need a whole new back end. we went to the junk yard and got a 377 but when we took it to the mechanic he said it wouldn't work because we need a 355! is this right or is he just trying to get $1300.00 out of me? from what i understand it'll just set my odometer off some, which i'm okay with me because i don't plan on selling. any responses are welcomed! thanks
jade

jeep never offered a 377 ratio to my knowledge...and no,you cannot mix gear ratios in your axles stuff will break

3.73 not 3.77 would most likely be the ratio on the JY axle...

But your gearing needs to be within 4% of each other. And none of the gearsets in the Jeep line-up are within 4% of each other. So if your front is a 3.55 then you need a 3.55 rear. Or you can't use 4wd without risking SERIOUS damage to to your T-case and axles. If you have an AWD equipped Grand... don't even think about running 2 different axle ratios.

You shouldn't have any problems finding a 3.55 equipped Grand, though...

As previously mentioned you cant use that axle with 3:73 gearing.

Your looking for a rear axle from a Grand with the 4.0L (3:55), you cant use an axle from a V8 equipped Grand... which will have 3:73.