You can use a 46RH/46RE transmission. They are also called 518. Essentially what it is, is a 727 with an overdrive unit. They have the 318/360 bolt pattern. They came out in 1988 or 89. Up to 95, they had a mechanical governor. 96 on up, they had a sensor and a soleniod that acted as a governor. Both styles use a computer though the 46RH, only 4th and lock up is computerized. On the 46 RE, all gear shifts and lock up are computerized. Also, both versions still use throttle pressure via a linkage to control shift feel. Just like an old 727/904.