Help with differential ID, please.

[krayzog]

I am about to order a bunch of parts, to rebuild my differential. I just want to make sure I have what I think I have. Any help will be appreciated.

My truck is a '61 C10 SWB, 327, 3 speed (on the floor now). It originally had an I-6, on the column. I know the engine/trans has been swapped, because my dad and grandpaw did it when I was a little kid (with me over their shoulder, on the creeper... in the way). I know I have a 10 bolt, non-posi, but, is it original or is it another swap that may have happened while I was learning to color in the lines and play well with others?

Also, I counted the ring teeth, divided by the pinion teeth and came up with 3.33. I've had 7,000 chevy trucks (maybe a slight exageration) and I've never heard of that ratio, did I do something wrong?

There have been other mysteries about this truck that I have yet to uncover, like...exactly what transmission it has (doesn't fit any of the sideplate diagrams I've found)...why the starter just decides not to work 1 out of every 4 times...and why the truck seems to HATE MY TOOLS!

I've been lurking for a while, and enjoying every minute of it, but this is my first real post. Again, any help would be awesome!

[Captainfab]

Welcome to the forum

Yes that is the original differential for your '61. It is commonly known as a Eaton HO55 or just a 55T. They were used from '55-'62. You are lucky that it has the 3.31 gears. Most of these seem to have the 3.90 gears.

From what I can see it looks like a pretty decent truck. And that's cool that it has been in your family for this long. You likely have some fond childhood memories in this truck.

[krayzog]

Thanks, Captain. That's exactly what I was needing. Another question; there is some slack between the ring and pinion, not alot, but I would adjust it/shim it if there is some way to do that in this style diff. Do you know. Thank you very much for your help.

[61_FL_Apache]

Is the diff making noise? If not, id leave it alone.

[krayzog]

It doesn't really make noise running, just noticed it kind of clunks now that I have the diff. cover off.

[Captainfab]

I agree with 61_FL_Apache, unless it is really bad and making noise, I would leave it alone. Trying to fix it would likely cause an issue sooner or later. IMO the best way to fix excessive backlash, is to rebuild the differential.

[krayzog]

Thanks, guys. Much appreciated.