To Posi, or not to Posi

[Corkwheats]

Hi Guys,

I have a 71 2WD F100 w/390 - C6, and it has a "highway" gear in it. It's like a 2.73, or something. This Summer, I plan to put in a 3.5, which is what this truck originally came with. This will be better for me, cause I do a bit of hauling/pulling here on the farm. I'm also hoping it will correct my speedometer.

My question - what basic benefits would there be to having a Trac Loc posi-type rear end? If I'm not racing, or doing any off road stuff, would a standard ring & pinion swap do me just as good? I know it would be less expensive. Is a Trac Loc rear end better for pulling in any way?

Thanks,
Bob

[hazelnut]

It's one of those things of weather or not you'll need it. If you ever go off road even if it's nothing but driving across a field then I would have it. Nothing worse than having a peg leg and getting stuck because you only have one wheel pulling, Then have to walk to get someone to pull you out.
The tire that's going to spin when you need traction is the one that doesn't have any.

[Madman]

My is for what you are saying you intend to use it for, I don't see the necessity nor need for a locker.

[ultraranger]

What do you want? That's the only thing that really matters.

I have a '69 F100 short bed Ranger with a 240, C-4 and had a 3.50 ratio in the 9-inch rear with a 28-spline open (single track) differential/28- spline axles.

I have a factory Ford Daytona 9-inch N-case 3rd member I bought in the wrecking yard back years ago. I pulled it from a 1975 Ford F150 4x4. It has a 31-spline, 4-pinion, Traction-Lok differential with 3.50 gears.

I haven't had a 28-spline Traction-Lok 9-inch differential in over a decade but, I have several Dentside 9-inch 31-spline Traction-Lok 3rd members, I've gathered over the years, in my personal stash.

I got a pair of 31-spline axles from a '71 F100 that had a Ford 9-3/8" rear end under it. I swapped the 31-spline Traction-Lok N-case and the 31-spline axles into the 9-inch rear end housing under my '69 F100.

It didn't really matter to me if my truck 'needed' these parts. It was a matter that I wanted them. --I already had the TL 3rd member. All I needed to get to install it was the axles so, that's what I did.

My stock C7AW-E, 9-inch, 28-spline, single track, 3.50:1 3rd member.



My old stock 28-spline axle on the left. 31-spline axle on the right.



My stock '69 C7AW-E 9-inch 3rd member on the left. '75 Daytona 9-inch N-case on the right.



N-case and 31-spline axles installed in the '69 F100 9-inch rear end housing.

[1970FordTK]

I'll just give you this example, I watched a guy with a dodge with a open deferential have to be pulled up the boat ramp cause his one wheel drive didn't have enough traction to get him and his boat up the wet boat ramp. This was on a concrete boat ramp, having a limited slip or a locker is worth the cost if you have to make a change anyway in my opinion. Any way just my .

[Corkwheats]

Thanks for the input, guys.
Gosh, after making a hay run today, I sure wish I had a trac lock rear end. It is the thaw up here - everything is muddy. It would've been nice to have that 3.5 trac lock rear end, I'll tell ya!
My rear end is the 9" 28 Spline C7AW.
I'd love to get a 3.5 trac lock, but don't know if I can afford it.
The Truck is getting rear seals, wheel bearings, rear brakes, etc. in about another month. If I had the rear end I wanted that was all good to go, that would be swell.
But, I'm chipping away. Thanks for sharing the knowledge, fellas.

Bob