New to site and Need Rear end advice

[dawsonthompson]

Hey guys I'm new to this site well at least to joining. I have been in the process of building a 66 swb My father bought me the truck my senior year in highschool for 1500 came with lots of rust no motor three speed trans i think and a clear blue Texas title. Body wise i have cut out and put in new rockers inner rockers cab corners rear cab supports and many different sections of the cab floor by bending/fabbing up my own patch panels. I then sealed my welds and rhino lined the inside and underside of the cab. Motor and trans wise i rebuilt a BBC 454 bored .40 over dome top piston 396 crank mild cam rebuilt some 396 head by putting new performance valve springs cleaning up the carbon build up and reseating the valves, aluminium intake, and then a Holley 850 double pumper for the trans i purchased a TH400 with a 2500 stall. The truck has many other parts sitting and more piling up since I've graduated highschool and started working.

However now to my question i have the stock rear end and know i need to upgrade to something beefier i want to do a posi but I am curious if i should purchase something like the eaton 12 bolt posi kit or go to the junk yard and pull a posi out of a later chevy and weld my perches to it. In yalls opinion what will be stronger easier to bolt in and if i do go to the eaton does my yoke change do i have to get a new one?? These might be stupid questions but honestly i have no idea and other forums didn't go as in depth as i would like to know at least the ones i read didn't

I will post pictures soon

[Captainfab]

There is absolutely nothing wrong with building the truck 12 bolt. They are a lot tougher than a lot of people give them credit for. As with any differential, their strength is not only relative to the power coming thru the driveshaft but also the tires on the ends of the axles. You could put 1000hp to it with skinny tires that are just going to go up in smoke and not hurt the differential. At the other extreme, you could put 500 hp to it with some wide and or tall sticky tires and blow it apart.

You just need to look at what tires you plan to run, what kind of power your 427 will be making and how you drive. Then build the differential accordingly. A posi or a locker will be a good idea and depending on other factors, a set of aftermarket axles may be in order, and possibly welding the axle tubes to the center section.

[verdell]

I'd have to agree on rebuilding the 12 bolt. One of my brothers ran a 468 BBC with Comp Cams Mutha Thumper hydraulic roller set up, 400 TH transmission and a 12 bolt posi rear with zero problems. Another brother currently runs a 396 bored .30 over with Comp Cams hydraulic roller set up, 700r4 and 12 bolt posi with zero problems. They both make pretty good power/torque and never had issues out of their rebuilt rear ends. These trucks ain't trailer queens either. A rebuilt 12 bolt is ok IMO.

[The Rocknrod]

http://www.quickperformance.com/GM-1...-12T_c_54.html
I bought a whole set up from them for my 12 bolt.
http://67-72chevytrucks.com/vboard/s...3&postcount=27

[andyh1956]

I use the Eatons w/ the replaceable clutch packs. Late model GM rear axles are gonna get you an Eaton Gov Lok. You don't want that.

[bpmcgee]

Dawson,

You could also look for a GMC truck rear end, which came with the eaton standard, and a posi optional. Might save you some time.

B

[dawsonthompson]

Guys thank you so much for responding made my day didn't think anybody was gonna respond to Me honestly and so about the 12 bolts they came in later model chevys? Or what and if so what year/make like chevy truck suburban car or what and if so i was told the rear ends are longer or something than the one that is in my truck so I would need to shorten it or just tub my fenders??

[dawsonthompson]

Also will post pictures soon

[dawsonthompson]

Originally Posted by Captainfab

There is absolutely nothing wrong with building the truck 12 bolt. They are a lot tougher than a lot of people give them credit for. As with any differential, their strength is not only relative to the power coming thru the driveshaft but also the tires on the ends of the axles. You could put 1000hp to it with skinny tires that are just going to go up in smoke and not hurt the differential. At the other extreme, you could put 500 hp to it with some wide and or tall sticky tires and blow it apart.

You just need to look at what tires you plan to run, what kind of power your 427 will be making and how you drive. Then build the differential accordingly. A posi or a locker will be a good idea and depending on other factors, a set of aftermarket axles may be in order, and possibly welding the axle tubes to the center section.

Ok I was told my motor was a 427 by the machine shop guy after I built it too but don't understand exactly how all of that gets measured up and what not can you go into further detail about that too?

[dawsonthompson]

Here is a old and not to good photo but this is all I have on this phone will find the many others from my old phone

That's the big block nestled up in there the exhaust manifolds hit on one side where a little nipple sticks off the manifold however I'm hoping that issue will be cleared up when I find some decent headers that will fit and also the valve cover have about a fingers worth of clearance before hitting the firewall on the cab other than that she bolted right in

[Heater63]

Welcome to the group neighbor.

I think your 12 bolt rebuilt with new guts and a posi will live as long as you want it too (depending on your right foot).
There is a TON of good information here. I suggest you research this site about running a big block, that is something I can not weigh in on.

Also, fyi, Captainfab is a great source of knowledge, (and sells good products too.)

[Captainfab]

It's just the combination of the bore and stroke. Your engine may not be an original 427, but installing a 396 crank into a 454 block makes a 427 cubic inch engine. It is actually a little more than 427 cubic inches since it is .040" over. It is probably around 435-436 cubic inches.

A 427 will rev a little quicker than a 454, but a 454 will make more torque.

Originally Posted by dawsonthompson

Ok I was told my motor was a 427 by the machine shop guy after I built it too but don't understand exactly how all of that gets measured up and what not can you go into further detail about that too?