Google it, lots of Fox terminators out there, more than you'd think. Pretty much, what you need to do is find an entire wrecked Terminator and a clean Fox, preferably a notch. It doesn't matter what model the Fox is because you aren't keeping anything. You swap just about everything from the donor car to the fox.
A clean donor will be between $6k and $8k if the seller is reasonable. You will not be able to piece one together for less than that. As far as the rearend it all depends what you want to do. You can use the IRS or an SRA.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.