my c4 transmission wont shift until it reaches highest rpm and wont shift into 3rd gear

i just put in a brand new 302 into my 69 mustang and put a 2400 stall converter into the transmission. once i started it up and drove it it will only shift into 2nd at 3500 no matter how little gas i give it. and it wont shift into 3rd unless im going extremely fast. sometimes it will shift into 3rd randomly but then come back into 2nd. does anyone have any idea what is wrong with it.

miss adj.kick down linkage.cable or a rod from carb down back of the engine to tranny linkage.also this transmission is noted for intermediant band braking inside flix material to thin flexing will break it not adjustuing the band and band ware is some of the cause.drop pan look for a clevis laying in bottom of the pan. i have rebuilt four of these my self.mustang is a peace of shit for a car it is a ford falcon orginally.302 engine damages c4 aluimane tranny to much torque.

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