Early top loaders were direct 4th. 77,78 offered a .81 OD. The early 80 top loaders with the aluminum case offered .81 as well as a .70 OD. So a lot of it depends on which top loader you have. Even if you have the direct 4th, the FE motor will go faster than you you can keep your 57 on the road and certainly faster than you can stop if it you have to make a panic stop. But keep in mind that the faster you go, the more gas it will guzzle.