Hi, i want to know what i need to change my rear end gears.

I have the 3.42 gear set and my car have a 2.73 on it. Can i bolt on or need to do modification?

 

Unless you have a 3.42 set made for a 2 series carrier,which yours is because you have the 2.73s' in it,you need a 3 series carrier or,the following is not recommended,a ring gear spacer.Also a rebuild kit for bearings,shims,seals,etc.Also all the tools to be able to do/make all the necessary adjustments/settings.

 

Thanks FirstYR.