[hpbongers]

Just got a posi rear with 3.23 ratio. Anyone know how to decypher the #'s. On the case there is a 1285542B. Also in two other spots, a G133 and a c2. Any help would be great. I need to id it to get the brake parts, seals and bearings. I was told it was a 75 or 70? I am going to put it on my 69 Firebird to replace the one wheel drive.

[hpbongers]

Just got a posi rear with 3.23 ratio. Anyone know how to decypher the #'s. On the case there is a 1285542B. Also in two other spots, a G133 and a c2. Any help would be great. I need to id it to get the brake parts, seals and bearings. I was told it was a 75 or 70? I am going to put it on my 69 Firebird to replace the one wheel drive.

[Chuck Jones]

The casting date of G 13 3 indicates that the housing was cast on July 13,1973. Model changeover is usually the last week in july and parts are usually cast a week or two (sometimes more) before the car is assembled. This rear end could be either a late 1973 or an early 1974.

Now for the bad news! This rear will not bolt in to your 69 Firebird. The spring mounting pads are different.
You can make it fit by carefully grinding the welds off the spring perches and welding the 69 perches on the later rear end. This is no job for an amatuer, so I would suggest having it done at a good welding or machine shop. The perches need to be spaced and indexed accurately for the rear to fit in the springs properly.

Save your empty beer cans! The Japanese need 'em to make cars!

['ol Pinion head]

Easier to just build off a '73-74 Nova 8.5 housing. They are direct fit, perch wise, on the multileaf 68-69 Bird & Camaro.

Axles in the '72-74 8.5 X-bodys are also slightly narrower than the 2nd Gen F-body axles. When built, will allow a little more tire clearance at the wheel lip. Having pitched more than my share of hacked & whacked 2nd Gen F-body hsg into 1st Gen hsg messes, just not real positive on 'em