bigredbrad

I have been reading Alan Colvins Corvette by the numbers and studying the C3 differentials available as well as the ratios. The question I have is regarding 1968-1970's where there are listed codes for non posi, posi and Heavy Duty Posi units. In 67, the designation is for posi and 427 posi, but in 1968, the 427 is no longer a designation.

For 1968 - 1970, what is the difference between a posi & HD posi? Physical characteristics? Sizes? etc?

I will have more questions after this initial one is answered.

thanks

bigredbrad

redvetracr

HD diffs had caps & bolts not u-bolts

bigredbrad

Ok, that makes sense, now what about internals?

Different size bearings? Carrier? Are the output shafts with the heavier cap a different size spline? etc.

Can the internals of a posi be interchanged with a HD posi? Or are they completely different?

thank you

bigredbrad

redvetracr

pretty sure bearings are the same, posi carrier is different, same spline, there is a posi carrier and a non posi carrier, they are completely different, you can (I believe) use a posi carrier in a non posi housing

redvetracr

PS: corvette-world.com (click on specifications up top)

Johnny C1C6

Call me stupid but I think I just got confused. I have a 60 Corvette posi rear end and my axles are like inch and a half to inches difference. I'm sure they only go one way but I was trying to find out for sure before I stuck them in there. Can someone tell me which is the driver side axle... long or short?

Alan 71

Hi J,
Welcome!
First Post!!
From the info available on line it appears the left side is the shorter while the right side is the longer.
1959-1964 Left 28 7/16" 17 3754207/3798183
1959-1964 Right 29 15/16" 17 3754208/3798184
Good Luck!
Regards,
Alan

tracdogg2

I realize this is an old thread but I wanted to mention a few points.
From 63 to 79 there are 3 versions of the differential housings. 63-64, 65-mid 66, and late 66-79. Housing are the same posi or non posi.
Big block stub axles are the same dimensions as sb but are threaded for caps and are about 6 points higher on the Rockwell hardness. The main difference was the posi carrier. HD units used a nodular iron carrier. Although it was stronger than the standard carrier it was still the small window design and weaker than the carriers used in 71-79. They were used in "F" code differentials.
Mike

David Mc

Dang, [rant on] I want to clarify terminology. The ring gear is bolted to the differential case. The differential case can be open or some type of traction aid type. The differential case is held in position by the carrier. The Ford 9" has a removable carrier as did the Eaton drives GM used. In the IRS Corvettes the carrier is bolted to the car frame. Many cars had integral carriers. aka "Salisbury axle" [rant off]

OK, I know everyone uses "carrier" for the case and "housing" for the integral carrier.

tracdogg2

It may be a little hard ordering parts that way,
You left out pumpkin, pig, plug, third member, center section, and drive unit.