64 gmc 305 spread between 3rd and 4th

[Cj92345]

finally got the gmc 4x4 driving good, when I first got it the tires where 29 tall and the truck seemed very low geared, now I've put 33's on and the the spread between 3rd and 4th seems drastic, really got to get her wound up to go into 4th....normal?
thanks

[cerealwars]

That's a pretty hefty tire diameter increase.

Re-gearing the rear end is the correct way to fix it.

These drivelines will put up with sustained loads pretty well though, so it's not like you need to fix it in any sort of hurry.

[TwoFiftyShifter]

My 82 has the 4 speed trans with 31s. 2.73 gears. You need to wind her up to go anywhere, but no overdrive needed. Never driven a 305 V6 but it probably gives up some oomph to a 350SBC in normal driving.

[Cj92345]

yeah, 60-62 is about tops, no tach but it seems buzzing
prior owner said he had it re-geared in the 70's to haul a camper on it, but couldn't remember what gears where in it or what he had installed...lol

[mongocanfly]

Truck looks good..!!....
1st I'd figure out what axle ratios you have in it...you can use a variety of methods to find out...Google how
And go from there
What trans do you have?
Regearing is a option as pointed out by cerial,,,,but you have to do both axles ,not just the rear, as I'm sure you know...