[illflem]

I highly doubt there are factory made larger replacement gears, they would have to be custom made and would cost a fortune.
You would be better off changing the rear (and front if if 4wd) differential gear ratios or buying one of these Gear Vendors under/overdrive, Facts.

 

[Jameson Bearden]

I agree with illflem. If you have the money an under/overdrive unit would probably suit you well

 

[rpage]

put 342 gears in it