Ok i have an 85 Firebird Sport Coupe Original V6TBI, Now 350 Chevy SB Comp cam 268 Fully rebuilt TH400 Fully rebuilt /w Shift Kit ex. racing transmission. It has the origianl rearend in it. All i know is its not good. I dont have the money for a complete new rearend so i was gonna take one from the wreakers, What should i look for what type of firebird? or camaro? Its gotta be posi with a lower gear ratio real good for street and strip use. whatever help u guys want to offer is much apreciated thanks guys?

Kevin

 

Here's my experience...

I bought an '84 3.73/posi/disc axle for $150, and put it underneath my '86 2.8 Firebird. I spent the usual cash to "restore" it (POR-15 paint, new axleshaft bearings/seals, new brake hoses, new parking brake cables, new pads), and then spent a ton more trying to get the rear brakes to work. And now, the posi inside, an Eaton gov-lock, went out on me. I was warned about it, but didn't think my V6 would ruin it- damn. Total cost is around $700 for the swap, and tomorrow, I buy a $100 junkyard 3.42/open/drum axle just to drive on for a while until I fix my "real" axle.

So Basically, I'm saying you might want to avoid swapping an axle in. You'd probably be much better off buying NEW 3.73 gears, a new posi, and having them installed. Dan B's (ws6transam) page is great for building up the 10-bolt, check it out: http://www.ws6transam.org/10bolt.html

Altho, here's the cars you'll find a 3.73 under:

3.73/posi/disc: (my axle) 82-85 Trans Am's and Z28's, with the optional engine (eighth digit of vin is "G") and a manual transmission. Careful; 82-83 brakes use SAE (standard) fittings, all 84-up f-bodies use metric.

3.73/open/drum: '84 Camaro H.O. ("5.0 Camaro H.O" is stamped on the left of the rear bumper)

3.73/open/drum: Any 4-cylinder f-body with the manual transmission

Warning! All those axles are pre-90. GM used a stronger 28 spline axleshaft starting in late-89. (89's can have 26 or 28 spline axleshafts) So if you don't want weak, avoid the 26 spline axleshafts. A pre-90 posi will do you no good, since it'll want the 26 spline axleshafts.

 

I dont care much for disk brakes rear Drum is fine with m. it rather disk but it sounds too much of a problem what type of cars ran 3.73/posi/


kevin

 

i parted an 85 firebird t/a sw6 and it was ho305 and 700r4 and it had a 3.08 posi disc

my 84 z28 305ho 700r4 is drum and i dunno if is open or worn out gov lok and its a 3.42 or lower geared, its quick ! did they really have 3.73 in these cars ? i know 3.08 for sure in the hottest 80;s pontiacs because it was tagged and all with 3.08 posi and i sold the axle for 25 bucks.... slap me...

 

Yep, if your car had a manual trans instead of the automatic, you would've had a 3.73/gov-lock posi/disc rear. And you'd know if your gov-lock is worn out; mine just went out, and I couldn't turn without a horrible BANG!

And CR-superchevy, in my original message to you, I just told you what cars came with a 3.73 posi.