well i have a 1975 f150 4x2 with a hopped up 390 currently getting put in it, anyway when i bought the truck the guy had put lower rearend gears in it, and i also got the stock gears with it, so my question is would the lower geared rearend be better than stock for laying rubber and burning up the 1/4 mile or should i stick the stock rearend gears back on it, thanks

 

It all depends on what gear ratios you are talking about, what size tires you're running, and where the powerband is on your new engine.

 

"lower gear" ratio means a higher speed rearend. However, many times people say lower geared rearend when they mean lower speed rear end. You have to determine which the prior owner actually meant. If he had put in lower "speed" (higher ratio) gears, reinstalling the originals will increase your mileage but will decrease your "get up and go" off the line. I hope I haven't confused he issue!!

 

the lower gears (numberically higher number) will help improve response, burnouts, and it will help with towing and hauling. But it will use more gas and wear your rebuild faster cause the engines will turn more revs.

 

I agree with swann79...Need to know the ratio first. But...with that said, I would say the originals. Unless they are higher than 3.50's. If the current ratio is in the 4's...use the "higher" geared rear.

PS...3.50 is higher than 4.10.

 

higher or lower "numeric" gears usually end all confusion.