Hey guys, does anybody know the code for a 373? I believe the code for 342 is SF? And location is on the passenger side towards the back of the car? Anybody got a pick up location? I rotated the tires around once Drive shaft goes 3 3/4 so that’s 373‘s
found code P3 0343?

P3 0343

 

If thats a 10 bolt cover, the axle has been changed. My understanding is the code should be stamped on the passenger side tube, on the part that faces the front of the car.

 

Rear axle codes are contained in the front of the CSM.

 

That's R3 - A 1970 type "O" rear. 2:56 posi

Updated - Agree that's not a type-o rear.

 

According to the 1971 Service Manual, the 10 Bolt 8 1/2 axle coded R3 is a 2.56 anti-spin. There are no P coded axles. To me, the stamp you show in the picture is R3, not P3

Being that your car is an A/C car, it would have come with the 3.23 or higher(lower numerically) ratio. Someone has swapped the original axle for the current 10 bolt

 

^^This^^

Information is contained in the 1971 Oldsmobile CSM (p. 0-6, Fig. 10A - Differential Identification Code)

 

so i thought maybe it was an R3 and it has 3:73 in it. So the hosing R3 is a 3:23 originally? Because of the AC
So is it definitely not the orig hosing with updated gears?

 

it is on the passenger side towards the front

 

The original axle would have had 12 bolts on the cover. Your current axle only has 10. That makes it a 71 or 72 corporate 8.5" axle housing. Originally having a 2.56 anti-spin (Posi). Someone has changed the carrier and gear. These are good axles, plenty of aftermarket support. And can be made to be very strong. They. have more parts available than the O axle you originally had, and are stronger. So unless you want original parts, its a better choice. Youd be looking for an SE(open) or SF(anti-spin) stamped axle for the correct 3.23 gearing used with A/C cars

 

It could also be the original 2-series carrier with a ring gear spacer. The only way to tell is remove the cover for visual inspection.

 

Thx! Yeah not that important