I have a 63 f100 with a 223 inline 6 with the four speed manual. I am currently working on rust repair and electric and have not thought much about a motor/tyranny swap because it runs and drives as is but the rear end seal is leaking and the trucks is reclined at 50mph. What is suggested a rear end swap or replace seals and swap gears? What gears would be best for freeway driving? I have a mechanic buddy who could come over and help. Just need to know what parts I need to acquire?

 

"Red lined"

 

Make sure its not your valve cover gasket leaking fooling you into thinking your rear mains out and I would suggest changing tire sizes first they make a bigger difference than you would think and you can go up to 33" on back for regular driving 32" if your working it ..... if you did change gears I would keep it between 3.08-3.53 depending on tire size

 

The warranty plate will list the axle code for the rear end ratio. IF the code is "12" the rear end ratio would be 3.89:1. If it's an "08" it's a 3.50, "09" would be a 3.70, "17" would be a 3.25.

Dentside trucks had some 9-inch 3rd member ratios of 2.75:1 or 3.00:1. These would be good for lower engine RPMs on the highway but not good for pulling a load. If you found one of these higher gear ratios (lower numerically) from a Dentside 9-inch rear, there's a very high probability you would have to swap the gears over into your 3rd member, since most Dentside 3rd members have 31-spline axle gears and yours would be 28-spline.

 

07 = 3.25-1 (1965) / 17 = 3.25-1 (1966/79).

 

Where is the warranty plate located? at a glance there is nothing in the door jams or on the engine compartment firewall

 

1961/62: Warranty Plate riveted to the inside of the glovebox door.

1963/79: Warranty Plate riveted to the left door face below the latch.

It may have been painted over.

 

Got it! Axel is a 12. Trans is a F.

What gears should I swap to for low rpm on flat roads / freeway.

Next question is what tranny would be better in this situation? Keep the four speed with granny or use the three speed out of the parts truck?. Really just trying to keep this 223 going it's running good plus I have a spare and I really like them.

 

So you have 3.89 gears. Your trans is 1:1 in 4th, as is any 3 speed you would find. If you are really adept at finding things, you might find a BW T85 or similar three speed with an overdrive unit on the back. Good luck with that. Numberdummy may or may not return to tell you exactly which of those your truck might have been available with when new.

The 9 inch rear axle is easy to swap out if you can find a servicable unit. See the prior posts about the axle spline count. You also need to get the right yoke on the front or have yours changed over.

What tire are your running? Taller tires are a cheaper way to go, but are a compromise as you don't get the same net effect as gears usually due to the increased weight of the tires. (harder to get them moving, harder to stop--rotational inertia and all that you know...)

 

Thank you for that info. I'm currently searching the site to decode the rest of my codes on warranty tag. Any quick links? I am going to move forward with ratio change in rear end.

 

Post the codes here, one of us will decode them for you.

 

If you're trying to source a 9-inch 3rd member/rear end gears from a Bumpside truck ('67-'72), all the 3rd members in these trucks will have a 28-spline differential --same as what your truck would have.

Most Dentside F100 ('73-'79)/F150s ('75-'79) had 31-spline differentials but, some did have 28-spline differentials.

All Bullnose trucks ('80-'86) with a 9-inch rear end had 31-spline axles.

There are numerous rear end axle codes. Many are consistent across body styles while some codes pertain to different ratios from previous years and can even pertain to different ratios within the same body style run.

The best thing to do is print out 9-inch rear end ratio code information and take it with you to the wrecking, to be able to decipher what the axle code means on a potential donor truck. --also realize, door tags can be missing or replaced with another door (if the truck you're looking at has the tag on the door). The tag on the 3rd member itself can be missing or the 3rd member could have been swapped out.

The highest 9-inch ratio I know of is 2.47:1. There was also a 2.50 ratio. With a six cylinder, the truck will be very sluggish starting off or when trying to accelerate with ratios this high. It will be a gutless wonder if trying to pull a load with these ratios but, would have low RPMs on the highway. 3.00:1 or 3.25:1 rear end gears would make a drastic drop in RPMs, compared to the 3.89s you have now.

I don't know anything about a 223 but if there's a modern Ford overdrive (built within the last 25-30 years) that will bolt up to it, that would be the best route to go and keep the current rear end gears.

 

F10JR330982

W.B. color model. Body. Trans. Axel
114 Y. F100. 66A. F 12

D.S.O.
72

 

F10 = F100 2WD

J = 223 1V I-6.

R = San Jose CA Assembly Plant.

330982 = 1963, assembled September 1962.

114" Wheelbase.

Y = Glacier Blue.

F100 2WD .. 5,000 lbs. GVWR

66A = Unit Body Standard Cab Pickup.

F = Borg-Warner T-98 4 Speed Manual Transmission.

12 = Ford 9" Rear Axle / 3.89-1 / 3,300 lbs. Rear Axle Capacity.

5,000 lbs. Gross Vehicle Weight Rating.

114 net HP @ 3,600 RPM

72 = San Jose (NorCal) Ford District Sales Office, where the original selling dealer ordered the truck from.

 

Wow! Thank you for your quick response. This is my second unibody and is going to be a keeper. Trying to go through everything right now to make it safe and reliable to cruise around the city. Thank you to all that responded.