Rear diff swap? Ass u me, they fit?

wanderinthru

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Mid Point Route 66
First Name
Shakey
Truck Year
81, 70, 75, 84, 89
Truck Model
K 10, C 30, K 20
Engine Size
350
Pinion bearings in the 81, K10 went out. Geared 4;10, 4 speed 465, with a 205(?) TC. It has the 10 bolt diff. I have 3 12 bolt truck diffs, 1 in a 78 K10, 1 in a 78 Blazer, both auto trans and 203s I believe. 3rd is in a 80 K 10 465/205.
Figure the 12 bolt in the blazer is the best, and vehicle that is basically scrap, so figuring on putting it in the 81.
Any one know if the drive lines will fit up? Looks like they do. If the drive shaft in the 81/10 bolt don't, should the drive shaft in the 80 work?
Not to worried about gear ratio, hope the blazer 12 bolt is higher, 3;83 ? Plan has been to put both diffs under the 81, when my roundtoit allows.

Thanks!!

Shakey
 

RoryH19

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Aug 21, 2015
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Texas
First Name
Rory
Truck Year
1987
Truck Model
R10 Silverado SWB
Engine Size
350 TBI
Pinion bearings in the 81, K10 went out. Geared 4;10, 4 speed 465, with a 205(?) TC. It has the 10 bolt diff. I have 3 12 bolt truck diffs, 1 in a 78 K10, 1 in a 78 Blazer, both auto trans and 203s I believe. 3rd is in a 80 K 10 465/205.
Figure the 12 bolt in the blazer is the best, and vehicle that is basically scrap, so figuring on putting it in the 81.
Any one know if the drive lines will fit up? Looks like they do. If the drive shaft in the 81/10 bolt don't, should the drive shaft in the 80 work?
Not to worried about gear ratio, hope the blazer 12 bolt is higher, 3;83 ? Plan has been to put both diffs under the 81, when my roundtoit allows.

Thanks!!

Shakey
The 12 bolt will bolt up to the 10 bolt truck. No issue. I believe the yoke is also the same size so the driveshaft will bolt up as well.
You may just want measure the u joint to make sure.
 

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