Trying to identify what is in Differential

Discussion in 'Got gears?' started by cobra2, Feb 16, 2017.

  1. cobra2

    cobra2 Well-Known Member

    1967 Buick Gran Sport 400 , I know the ring and pinion has been changed at one point. The numbers I have that I can see are
    10090-BP882390-10x39, It is supposed to be a Richmond , The ring is has 39 teeth, Looks like an auburn posi # 113021 13, also stamped is 504014, Its 10 bolt cover, 10 bolts holding the ring gear, on the differential where the cover goes on on the left side is stamped P on the right side is D.
    Now on the front side upper top of differential its stamped 293, other then that can't find any other numbers. Need to put in at least a 3.36, I think this is a 3.90 in it now but not sure. Any help would be appreciated. Thanks Craig 20170216_145708_1487288539643.jpg 20170216_145700_1487288540511.jpg
     
  2. BrianTrick

    BrianTrick Brian Trick

    8.2" BOP with 3:90 gears. Looks like Motive gears and an Auburn unit. I know two people that are currently looking for 3:90 gears like that. Let me know if you remove them.
     
  3. cobra2

    cobra2 Well-Known Member

    Ok Brian I will and Thanks , they will be coming out for sure. The3.90 will not work out where I live with the stock trans Eng tachs why to high at 70 and 75 mph, need to lower it.
     
  4. monzaz

    monzaz Jim

    10 bolt 8.2 BUICK rear the caps are a dead give away. AND they actually put the caps back on correctly. :)
    113 is a Auburn HP posi unit (last three digits in your given number off the unit...
    8882390 88 is motive gear 82 is 8.2 and 390 is 3.90 ratio (edge of the ring gear
    10 x 39 that is your pinion divided into your ring 3.90 ratio

    So 2 have confirmed i think your pretty good to go with this info. :)

    Jim
    J D Race
     
  5. monzaz

    monzaz Jim

    ------------------------------------------------------------------------------
    I would overdrive the trans and leave the gears if they are quiet.
     
  6. FJM568

    FJM568 Well-Known Member

    I know this is the gears section and not the transmission section, but you could swap in a 200-4r overdrive trans. It has a .67 4th gear which would give you a 2.61 final drive. More expensive, but it would give you the best of both worlds. Lower rpms on the highway, but really responsive stoplight to stoplight.

    Edit...oops, somehow missed monzaz's second post.
     
  7. BrianTrick

    BrianTrick Brian Trick

    The two people that I know of,that want 3:90's for an 8.2" did just that.They have converted to a 200-4R.
    Not sure what trans you have,but when swapping from a TH350 to a 200-4R,you need to shorten your driveshaft about 1/2" due to the slightly longer body of the 200-4R. I know it doesn't sound like much,but the shaft will bind if left at stock length.
     

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