it runs but is missing 4th gear and all the motor mounts are shot and either the transmission or rear diff is making a little noise. I bought it for a top gear type rally challenge and my budget is $300 so i need to figure out a few cheap mods. it has an aftermarket stereo in it which i think i can resell for $100 to get a little more money for it but will i be able to run the 4 bolt rear diff and are there any other cheap mods i can do to boost power output?