Semper (our 57 Dodge p/u with a 230 flathead six) is geared really low for use on a farm. He has 4:10 gears in the rear, so his top speed is 45mph and he has to scream to get there. And first gear is so low it's practically useless.

I found a good rear with 3:23 gearing and am thinking of swapping it out. I'm not after speed, but would like the engine to run at lower RPMs on the highway. Is this too big a change?

Pete