Re: Stock rear gear ratio info
 

Here is a 70 C10 power team chart for you. It really helps to post what year and series you have when asking a question like this.

Re: Stock rear gear ratio info
 

Thanks Tim, but yes it is a 1970 C10. I didnt know if mine had a different ratio than 3.07 because at 75mph the truck runs at about 3800rpms or so. I do have a built TH350 and 2200 stall converter however so that is probably part of the higher rpms.

Re: Stock rear gear ratio info
 

I have a 71 C-10 with a 307ci and the rear gear is 3:08...
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Re: Stock rear gear ratio info
 

Tim (or anyone) do you have a chart like this for a 68 K20?
I have a burb that was a 6cyl 4spd and a pickup with 327 240hp 4spd
They both have the 10 bolt rear.
The truck screams in 4th gear at 50mph
Thanks

Re: Stock rear gear ratio info
 

Thats an easy one, 4.57:1.
All you needed to do was click on the link in my signature, most are there.
http://67-72chevytrucks.com/vboard/s...05&postcount=5

4.57 gears spinning a 31" (stock 7-17.5)tire @ 50 mph = about 2475 rpm, that isn't exactly screaming. The indirect drive T-221 t-cases were never quiet.

Re: Stock rear gear ratio info
 

Thanks, I found the link right after I posted. So the T221 makes that jet sound normally? It starts whining at 40 and close to 50 I need ear protection.

Re: Stock rear gear ratio info
 

Have you checked for the proper fluid and level at all the driveline locations? The front axle, both cardon joint balls, transfer and rear axle have a 6k service interval per the driver's handbook pgs 55-57. SAE 90 dino covers most people's use of these trucks. If, with verified correct gear oil and level, its still objectionably noisey I'd look into wear and excessive clearance issues.

Have replacement parts in hand before pulling anything apart.

The idler and output shafts should have zero end play, as in 0.00" is considered ideal as measured with a dial indicator

Suggested reading
68 Overhaul Manual pg 7-111/PDF pg334
68 Service Manual Sections 0 and 3

Re: Stock rear gear ratio info
 

I've checked front and rear ends, trans and transfer case. All topped up with 90w

Cardan joint balls?


The noise is worse under load, it quiets a bit when I let off the gas, clearly coming from transmission or transfer case

Re: Stock rear gear ratio info
 

The cardon joint balls are the front axle shaft u-joint swivel housings, they have seperate filler plugs L&R and in checking the driver's handbook are to be filled with SAE140 vs the differential's SAE 90.

Re: Stock rear gear ratio info
 

I always thought 3.08 and the granny 4 speed was a sweet combo. No need for overdrive and can still pull a house in first. Just watch the gap between gears!

Re: Stock rear gear ratio info
 

Suggested reading and in hand resources.

Re: Stock rear gear ratio info
 

Thanks, that's great I wish I had them. Unable to download the manual onto my phone. Just need to see diagram or know where fill is for cardan joints.

Re: Stock rear gear ratio info
 

Here...