I got the 3.03 three-speed transmission back in my 65 F100 352, and something didn't feel right. A kind of binding popping vibrating feel, worse in reverse. Felt like the driveshaft was out of phase or the slip yoke was bottoming out. After a thorough inspection of the shaft, I decided it was not the culprit but just for kicks I ran it in gear, in the air, to listen to the bearing and see it running true. Then I noticed that the Left rear wheel that was spinning had a wobble to it. I know one of the wheels isn't true. I went to stop that wheel so the other would spin and that is when I heard the popping from inside the differential. ;-[
I'm fairly certain there is a broken spider gear or two. Luckily I have not been able to sell all of the truck that I am parting out and was able to pull the pumpkin last night and find an (almost) pristine gear set! I figured to change the axles along with it and am on hold trying to find axle bearings since one of those is roached. I have mine mostly out, just waiting for the grease to drain, and it is thick, black, and slow. I was thinking about changing my gear ratio anyway for lower RPM on the freeway and the new one is supposed to be a 3.25-1 to replace the 3.50-1 that my truck came with. I will count the gears and do the math to confirm, but it's going in either way. I Will post some pics when I can see the carnage...

 

Sorry for the carnage. It is awesome when you have the extra parts though.

 

There is a bit more to it than just changing the pumpkin.

Hobo

 

BCA 514003 fits most of 57-72 28 spline 9 inch

 

You are correct. I changed the pumpkin. I cleaned out all the old shiny gear oil that was the consistency of warm grease. I replaced the axle seals, (National 51098)
One axle bearing (national 514003 made in the USA) because I could only find one, I'll put the other in later it's really the easy part. I replaced the copper sealing washers for the pumpkin studs and sealed it with black permatex silicon. Filled it with 140W gear oil. Changed the motor oil as well.

 

Turns out that there was no visible carnage to show. In the 9" diff, the spider gears are well hidden. Now I have rebuilt a number of differentials as a working mechanic but I don't recall ever, EVER fixing a broken nine, and am going to need to open my shop manual to get in there. I guess that is just a testament to how tough these rear ends are.

 

Back when big teenager took several out, spider shafts , spider gears , axle gears. Broke adjusting cap once. 63 F100 292 T98.

 

I had a similar truck back in the day. Shortbed 62 uni with the same drivetrain. I broke the nine and just replaced it. Got a deal on a Dasna 60, never broke that one!

 

My '66 developed a sudden shaking in the rear end. Luckily in was at a slow speed. 3 teeth broken on the pinion gear, (Dana 44)