Well i'm bored and was wondering what would happen if I ran this gearing.

 

You would be pretty fast up to about 80, then be just about done.

 

30 mph in 4th? No traction? 5 mpg?

 

Hell 80 I was thinking more like 50, take off would be insane, But you couldnt take it on the highway becasue constant rev. of the motor would cause some serous damage. If I were you Go 3.90 I think that what Im gonna run. Right in the middle of a 3.73 and 4.10.

 

you'd have less problems towing. might be good for dirt tracking, but that's about it.

 

I thought a higher gearing would would be better for top end. So you're saying the 3.42 rear I have now is for top end or more low end?

 

Yours is better for Top end.
Higher the number=more low end
Lower the number=more top end

 

ha you would be tached out around 45

 

Get you some 4.10's and then a nice cam.... you should be alright..

 

Max. speed would be as if he had 3.90 gears and no overdrive (5.57 * 0.696 = 3.87672). Using stock tires, he would be turning about 4200 RPM at 70 MPH and his max. speed, assuming a redline of 6000 RPM, would be about 100 MPH, about where the stock PCM tune limits the truck.

Not all that bad IMAAHO.

n.b. that many passenger cars in the 1950's and 60's would turn around 3000 RPM or so at highway speeds. It's only been since the common use of overdrive in the mid 1970's that we've seen the now typical cruising RPM's of 2000 or less.
(for the purists yes I know they had overdrive in the 1950's, but it was an option that most cars did not have)