i dont know the specific's of the MTX-75, but it sounds like you blew out the differential. but like i said i dont know exactly what part of the tranny the speedo gets its info. But if it will go in gear and the speedo goes up and the car does not move, it is most likely the Differential. If you do decide to replace it, get a performance one so that this stuff dont happen again

98.5 Black SE ATX S&B filter, SVT MAF, optimized SVT TB, mesh grille, removed orange reflectors, painted rear reflector, gutted pre-cats, optimized SVT LIM, 19lb injectors, resonator removed cant afford an svt but lookin for 1 in nc