What else do i need

[gonzalo medina]

I have a 72 ford f-100 390 c6 I was told 325-350 to keep mpg and freeway drivng reasonable. Any sugestions the engine is freshly rebuilt 650cfm edelbrock carb with mathching manifold and hooker headers. If I buy the third member assembled all I need is a gasket and oil right? Anything else well I am in there to prevent futor surgery's in the rear.

[fordman]

if your replacing the third member that is all you need. some people suggest to just use silicone for a gasket. i may try both for a good seal on mine because it has leaked in the past.

[390Nut]

While you're in there you might as well get new axle seals, also. They're quick and relatively painless to install, and if yours are the originals, it's only a matter of time before they go bad, especially since you;ve pulled the axles and disturbed them. About $15.00 for the pair, if I remember correctly.

Might take a good long look at your axle bearings, as well (the ones pressed on at the hub end of the axles). Most likely being quite old, they could be ready to go soon as well, and if they are loose or show signs of wear, get new ones pressed on. Worth it in the long run, considering yours are probably 33 years old now.

3.50:1 gears is a great compromise for the highway and for light, infrequent towing. RPM's aren't much higher than the 3.25's, but you get a little more off-the-line power for getting moving if you're towing. At 65mph (indicated) I'm running about 2600 RPM, but I have a 4 spd, so your C6 might change the actual RPM a bit.

[FORDification]

If you're planning on buying an assembled third member, just be sure it's spline count matches your axles. You don't want to buy a later third member set up for 31-spline axles only to bring it home and find that your 28-spline axles won't fit.

[flyboy2610]

I would replace all the oil seals, as well.

[gonzalo medina]

Indeed the third member will be 28 spline 350 ratio. I am blowing 500 on a completly rebuilt ready to go with warranty. So oil seals axle seals and new axle bearings right. Does anyone know where to buy them and what info I need to get these? 1972 f-100 9'' 28 spline drum brakes.

[390Nut]

If you have a NAPA around, they carry the axle seals and bearings. Not sure what oil seals you would need besides those, if the differential you're getting is all new. Some say silicone is the best to prevent leaks, some say the gasket prevents leaks the best. I used both when I put my 9" back together, and that area hasn't leaked a drop since. Wish I could say the same about my pinion seal, though

[gonzalo medina]

Super thanks guys, I don't know what I would do without the site.

[mrung0wa]

If you plan on doing any towing on a regular basis you can't beat 3.73's!

I've had 'em on my 75 F100 and my 76 Bronco and plan on changing the 3.50's in my 69 just as soon as I can.

Lawrence