I am running a 110 amp alternator, but i want to run it to the factory amp gauge, but if i do this it will fry the gauge, is there a resistor i can run to keep this from happening, or any other usfull ideas.
It is not a resistor you need; it is a larger shunt. The shunt is the metal strip that bridges the two lugs of the meter. For 120 amps, you will need a shunt that has 4 times the cross section area as the stock 30 amp one.
You need to upgrade the wire size and fusible link from the alternator to the battery to match the higher current.
A better idea would be to move the shunt outside the cab by using the fusible link as an external shunt. This is the way Toyota wired the meters on '78 and later FJ40s. Get a couple feet of 120 amp fusible link from NAPA and use it to replace the original one. Hook the new alternator output to the chassis side of the link. Remove the internal shunt in the meter and run 2 new 18 gauge wires (both fused with a 1 amp fuse) out to the fusible link. Connect one wire to the chassis end of the link and the other end to the battery + end of the link. If the meter pegs during high charging, shorten the length of the link.