axle swap, fix opinions needed

[choptop]

ok guys heres the story. Last year the rear axle cratered in my red truck. The pinion nut came off and trashed the gears. I swapped the axle with one from a parts truck (85 blazer) just to find out it was bent. Well I acquired a 12 bolt (free) to replace the 10 bolt with and upon inspection today, I found the 12 bolt is a 3:07 (43:14) and I need 3:73 to match the front axle.
 Whats best route?:
  1) use original housing and axles and swap in ring and pinion and related parts from bent axle
  2) rebuild 12 bolt with new ring and pinion

Ive attatched a pic of the 12 bolt and have questions there:
  what is the spring setup in the middle for?
  will it swap and work in the 10 bolt axle?
  Are the back plates and drums the same on the 10 bolt and 12 bolt? I need drums for the 12 bolt and the ones on the 10 are brand new
  Thanks guys for your help, Im trying to get this done before a show on the first of May
 

[howlinwolf]

if you want to go to a show, why not stick it on, and drop the front shaft off, so you can go, and figure it out afterwards.

[joesgarage71]

springs=Posi

[VileZambonie]

You'll need a conversion U-joint. You have a limited slip differential so that's a plus. Get a 12 bolt truck ring and pinion along with an installation kit. I can't remember if the backing plates will swap over from the 10 bolt to the 12 bolt but I think they do. It's been so long since I did that I honestly forget. I'm sure someone else will chime in on that.

[howlinwolf]

dont forget the straps for the rear end, if yours didnt. i had to buy some today

[choptop]

You'll need a conversion U-joint. You have a limited slip differential so that's a plus. Get a 12 bolt truck ring and pinion along with an installation kit. I can't remember if the backing plates will swap over from the 10 bolt to the 12 bolt but I think they do. It's been so long since I did that I honestly forget. I'm sure someone else will chime in on that.

Best place/price for ring and pinion w installation kit? Chris, do you have them?

Howlinwolf, what straps are you refering too?
 Thanks guys

[VileZambonie]

Give these guys a try

http://www.ringpinion.com/

[choptop]

Thanks, that brings up another question. it sasy "this is a thick gear set for 3:42 and down carrier"
Is that numerically down or gear ratio down. Since mine is the 3:07 gears, I assume I need the other gear set. Is that right? Sounds like a dumb question, but it doesnt make sense to me.

[VileZambonie]

If they were smart they would be referring to numerical.

[howlinwolf]

where my u joint bolts to my rear end, there are 2 straps or clamps or whatever that bolt it on. just make sure you have the right side.

[choptop]

where my u joint bolts to my rear end, there are 2 straps or clamps or whatever that bolt it on. just make sure you have the right side.

Gotcha, and thanks for pointing that out. I do need to get some

[SUX2BU99]

If you  have a 3.42 or numerically-lower (like your 3.07 ratio) then you would need a 'thick' gear set to run the 3.73 gears. I went through all that last year.......3 times 

[choptop]

Thanks guys, that what I needed. I tried to swap axles on the 10 bolt today, but the housing has to be bent because it binds up severely when it meshes with the inner spline, plus, its a 3:07 gear as well. So, if Im gonna have to buy gears, it may as well be the one with the limited slip. Ill start on it tomorrow. Im gonna redo the bearings and seals. Ill probably just run the 3:07 for next weekend because I dont think I have enough time to order and install the gears before then.
 This leads to new questions:
   Will the u joint straps from any of the 12 bolts work? I have a few, but they are 5 bolt axles. If not, where to buy?
   What lube do I need to run with the limited slip?

[choptop]

Vile, hook a dummy out please and tell me which install kit I really need please>
PK GM12T or BK GM12T or the master YK GM12T

[VileZambonie]

You can run regular 80w90 just add the friction modifier. U-joint straps can be bought at any auto parts store. http://www.rockauto.com/catalog/raframecatalog.php?carcode=1296121&parttype=10437&a=FRc1296121k634492