tsillay is just about right on the money. It's the RATIO of unsprung mass to sprung mass that seriously affects the RIDE qiality. This in turn has a direct affect on the handling qualities.

Unless you are hammering out serious V8 type hp, the use of a Fraud 9" diff will only succeed in screwing up an otherwise good car.
Chris

Tsillay and Dodgeman are right on the button (as ever)

Worth thinking about also is the effect on polar moment of inertia if you have large massea at either end.

You might have 50/50 weight distrubution, but the direction changing properties of the vehicle will be RS.

I saw a mazda 1500ss converted to chev 12 bolt rear so he could use the cut down diff housing to get the desired ratio gears.

The car had all the problems described and would not turn then developed massive oversteer. The car was a disaster and scrapped by the owner.

Feral----these are the classic symptoms of what happens with a large polar moment of inertia---when it starts to rotate, just about nothing can stop it.

Keep all the mass as close to the middle as possible!

I have put in a bluebird center - this will sit behind a heavily worked A15 and four speed box.
It all depends on your budget, I've seen a couple of neat cut down Commodore conversions in Datsuns. That would be a happy medium (if your happy to have holden parts in your car that is)

WHY WHY WHY would you put one of them over weight, over engineered ,H/P robbing things in.You need to waste 10 to 20H/P to turn them,so think a bit (130hp minus 20hp what a waste).

I think he has the message now. The simple fact is that a well engineered car is a matter of balance, You use the component that will do the job that you need it to do, but nothing more.

The Bluebird diff center should provide you with a 3.9 to 1 ratio in the 1200 Ute rear axle housing. You may eventually break it if you really try hard, but for regular hooning about, it will serve you well & long, after all, it is what is used in souped up Bluebirds, & they are heavier & have 2L engines.

The Hemi in my 33 coupe will be good for about 325hp in a 25cwt [1.25 toonies] car & even then i will not use a 9" Fraud rear axle. I'l use an 8-3/4" Chrysler one.

Whats the word?..................Balance.

Here's one reason to use a 9": 500 lb ft of torque. There aren't too many 1200s with this much torque, but here's one.

If you are running a V8 in your 1200 -- all four of you out there (!) -- the Ford 8.8" is much better, a lot lighter and it can handle way over 300 lb ft torque in stock form.

I think so many rotary 1200 racers use the 9" because:
1. They are using drag slicks which shock the drivetrain
2. the 9" is one of the least expensive to modify, if not the least expensive

V8 powered 1200 #1
V8 powered 1200 #2
V8 powered 1200 #3
V8 powered 1200 #4
OK, so maybe #1 could really need something as strong as a 9" rear ...

how about a hilux diff if so how hard are they to engineer and do they cost alot thanks all so i will be running a ca in the datto

good luck, the hi-lux one thats fits is bloody rare now, as are the lsd packs for em, better off cutting down something i guess, if i was doin my CA id just go a h190 and maybe get a lock rite locker or something similar