Which Years Fit for Diff Swap?? I have a 71 1/2 Ton 4X4

[Dirt Racer]

Hi I have a 71 Custom Deluxe 4X4 1/2 Ton, it has 307 gears, (sucks), I want better pulling power, I heard you could swap later model diff housings (up to 87 as I remember), with little trouble, I remember being told one end was a direct bolt up and the other you had to change 2 brackets. This also gave better brakes & steering too. I'm after it for the better gears 4.10's at a minimum!

I think I got it fingered out help is always welcome!!!

Thanks!!

[Senator350]

welcome dirt racer!

if you want to upgrade, you should be thinking about a 14bolt Full Floating rear axle. they are a 1 ton axle with a 10.5" ring gear, accepted as being VERY capable. They are easy to find, and aftermarket parts are readily available everywhere you turn. Best part about a 14BFF is they are a direct bolt in.

There are 2 styles of 14BFF to pick from concerning brakes, 88 and earlier, 89 and later. The 89 and later have brake drums that can be removed without pulling the hubs... so obviously, you want the 89 or later.

And there are 2 spring perch widths, 1ton @ 40.5", and 3/4 ton @ 42.5"... Obviously you want the 1ton, because your spring perches are 40.5"... that's what makes the 14BFF a bolt in.

You shouldn't pay more than $100 dollars for a 14BFF with gears and bearings in good condition. If there is play in the R&P gears, save yourself the headache of fixing the problem and find one in good shape.

The part # for R&P with 4.10 ratio is AAM 26054993
I'm not dead sure if you can see the # on the outer edge of the ring gear or not. If you can, you can just pull the cover and spin the ring gear until you can see it. If you can't, you can have somebody hold one hub in place, mark the top of the other hub with a grease pencil, then turn it until the pinion has made one full turn. the number of turns of the hub is your gear ratio.

Most 14BFFs came with either 4.10s or 4.56s, so you have a good chance of finding what you're looking for.

if you are in NY, i'll trade you my 14BFF for your old 12bolt... even steven.

if not, happy junkyard hunting!

and remember, always buy new U-bolts to hold your axle to your springs!