Just need alil help with my truck

[hotrod_991]

ok first off i have no idea what model my truck is. the vin decoder says that is it a heavy half and came with a 350 4bbl factory. Manual windows locks. I am just curious cause until recently i called all squares silverados. Now i know there is a diffrence.

Next. I have the 10 bolt rear end. And am wanting to get a posi unit for it. does anyone know what spline there are? Also what is the best setup to you? lil bit of a budject but need a complete backage. Also some 3.73 gears.

Lastly what models and years would i be able to find a 12 bolt posi in teh junk yards?

Thanks for all the help.

[cor86]

Is it the 77? It should have 28 spline axles. I would get a limited slip, and not a locker. I would go with an Eaton/Richmond gears. Shop Summit and Jegs, they have gear packages. I think most of the 12 bolts were in early trucks (73-75), but were used from 73-80, or so.

[hotrod_991]

will the limited slip still lock bot wheels when i lay on the loud pedal? My dad built me a hot 355 and th400 so would like all the traction i can get off the line and still be drive able ie no wheel drag when turning. ill look at summit and jegs tonight. will my 10 bolt still be strong enough versus the 12.

[cor86]

Yes, it will turn both tires, until the clutches burn up. A L/S offers a smoother engagement, but allows for some slippage. A locker is on-off, not smooth, but somewhat indestructible. Personally, I would just upgrade the existing 10 bolt with a L/S and gears. The benefits that a 12 bolt can offer are not really worth the price it will cost. If you really just want to spend the money, I would upgrade your 10 bolt to 30 spline axles, from a company like Moser, and rebuild the whole thing.

[hotrod_991]

yea i would really like to rebuild the whole rear end its just not in the cards as of right now. I just need get get both wheels turning. When you say burn up. Is that common? i dont want to get an L/S and have it toasted in less than 6 months.

[cor86]

To be honest, I have never found a piece of equipment I couldn't destroy with the proper amount of abuse. Use some good synthetic diff lube, with the right amount of L/S additive and it should last 100,000 miles, or so, as long as you aren't using a trans brake, or constantly doing holeshots. The L/S manufacturer will recommend what lubes to use. A good diff cover, with fins, will also help some, and look good too.

[N2TRUX]

If your truck is 77 it should have a 12 bolt.

[hotrod_991]

cor86~thanks and yea im pretty good at breaking stuff myself. I am not running trans brake or anything like that. just a 2500 stall and its more of a dd toy so wont be at the strip too much (well thats the idea right now anyway

N2TRUX~that is what my dad and i thought aswell but when he got uder it found out it is a ten bolt so some one must have swapped it out at some point.

[cor86]

Originally Posted by N2TRUX

If your truck is 77 it should have a 12 bolt.

Were all 73-80 1/2 ton 2WD trucks equipped with a 12 bolt, or was it an option?

[hotrod_991]

ok I been looking at l/s for hours now and seems like all the 10 bolts are 8.5 and are for 30 spline. the 28 spline i found is for the front axle of a 4x4. Is there a way to know waht the spline is with out opening the diff? Should i just order the 30 spline and hope that its correct cause that seems to be the most general one?

[cor86]

Someone correct me if I am wrong, but I don't think the 5 lug 30 spline 8.5" 10 bolt appeared until 1988, which has different pads and shock mounts. If that's correct, yours is definately a 28 spline, unless it has been welded on. As for finding one, Eaton makes one and the part # is 19557, or EAT19557. If it was me, I would open it up before I ordered it, to make sure.

[hotrod_991]

yea deff nothing welded under there. I will look up those eaton numbers. I know it would be best to open it up. And i know i should. Im just in the phase of the build were I am gathering all the parts i need at one time online and sending them to my dads shop. I am still in Iraq for another month or so and will have about 2 weeks to assemble test and tune the truck before its shipped to TX form MT. The build thread is going to be alot of fun to do.

[cor86]

Well, good luck with the build. I can't wait to see it. Thanks for your service and be safe over there.

[hotrod_991]

ok so got a picture of the front side of my diff and it is stamped GM08 does this help with figureing out what spline my axles is? thanks