What's my rearend?

[DoobieBrother]

Hey guys. Starting to clean up differential and working on figuring out a few things including what rear end gears the truck has. Take a look at the pics of the id markings and let me know if any of you know what it is. Thanks in advance!

[DoobieBrother]

Yes. It's 12 bolts. And I believe 1/2 ton. It's a `68 Chevy C10. Just curious about gear ratio.

[Solver]

If you wire brush in the area pictured there should be 3 letters and some numbers. if you can give me those numbers I can tell you the ratio and year

[1969k10stepside]

Pull the cover and get the numbers off the ring gear.There is a list of numbers on it and in one area it will say 41 11,etc.Then look in the below list
Ratio 2.56:1 - Tooth Combination 41,16
Ratio 2.73:1 - Tooth Combination 41,15
Ratio 3.07:1 - Tooth Combination 43,14
Ratio 3.08:1 - Tooth Combination 40,13
Ratio 3.08:1 - Tooth Combination 37,12
Ratio 3.31:1 - Tooth Combination 43,13
Ratio 3.36:1 - Tooth Combination 37,11
Ratio 3.42:1 - Tooth Combination 41,12
Ratio 3.55:1 - Tooth Combination 39,11
Ratio 3.73:1 - Tooth Combination 41,11
Ratio 4.10:1 - Tooth Combination 41,10
Ratio 4.11:1 - Tooth Combination 37,9

[Robznob11]

looks like a stock 12 bolt judging by the cover, if you take your rear cover off on the ring gear will be stamped the ratio, if you don't know what the ring gear is its that big gear that sets in there sideways, looking strait at it when you pull the cover the ratio is stamped in the edge of it you can turn your pinion yolk by hand to rotate it around tell you see the # it should look like this 10:41 , could be diff #s but you get the idea, then all you have to do is divide the big #by the little one to get your gear ratio 41 divided by 10=4.10 gear

[Robznob11]

69k10 musta posted a split second befor me

[GREASEMONKEY72]

best way to tell is to get the numbers off the ring gear, plus the fluid could use a change anyway im sure

[DoobieBrother]

Fluid change and gear inspection is on the immediate plans. I just got out there tonight and started wire brushing off some surface rust. Everything that got brushed is now soaking in penetrating oil. The first of many hours in cleaning and refinishing everything chassis related. I'll go look at the axle and see what I can see. Too late too get after opening diff tonight.

[DoobieBrother]

Ok. Either I've gone blind, or there are no markings on the axle. Only the stuff I've shown above. Unless it's directly on the top of the axle. But I'm tired of messing with it tonight. Guess I have to wait till I pop it open unless anyone can figure from what I've given so far.

BTW, thanks much for the extra number info. I'll probably pop it open this weekend unless I get time before that.

[DoobieBrother]

Well, got the differential fluid changed tonight. Looked over everything and it looks like I have 3.73's, which is what I was hoping. And the gears are in good shape. (I think). Here's some pics of what I found after cleaning up a bit. Let me know if you agree that everything looks fine. Cleaned it i up a bit more before I put things back together and filled up.

Also a couple of other questions:

• How do I tell whether it has posi, limited slip, or what?
• How much torque can these standard gear handle before you need to upgrade?
• Oh, and I hope I did this right. I applied the Permatex Ultra black to the back of the pumpkin, then layed the Fel gasket on top, then bolted cover on top of that. Wasn't sure which side of seal Permatex should be on, but decided that order based on how the old seal came off.

BTW, the numbers found were...

3817778 11:41 GM 11-67 2

[jay_shy]

You have an open differiential there.

Posi and limited slip are the same thing.

Jason

[djw32]

Solver,
Can you help me out?
1970 chevy c-10
TDE 0120

Thanks, David

[glock35ipsc]

Looks to be 3.73's Doobie.

[Ole Blue 68]

Hey Doob,

I've got a cleanup project like this one on my "to do" list. How much trouble did you have getting the diff. cover off? I'm kind of dreading that part which is why I haven't done it up until now.

Ole Blue

[DoobieBrother]

You know, I was expecting the same thing. Suprisingly, though, it came off very easy. I suspect, though that it was partially because the day before I sprayed all of the bolts really well with pentrating oil. Then when I was ready to do it, I attached one of those round wire brush type bits to my drill and worked everything over a bit. Figured it was the beginning of my efforts to remove all the surface rust junk. When I did actually put a wrench on the bolts, they came off nice and easy. Then the remaining seal shaved off with a straight edge with no problems. I used brake cleaner spray to clean it all out before going in with new synthetic.

[Ole Blue 68]

Thanks for the info! I really ain't looking forward to messing with those bolts but I'll make sure to give them a good shot of PB the day before like you did.

[combustion]

not related side note =P

lol. if you look at the title of this post in a different sence it sounds goofy lol