My '69 was originally a Malibu 350 automatic. It also has a 12 bolt. Could this have been original?

Yes,

That can be original. I've got the same on my 69 Malibu with a 350cu/tubo 350 trans. I have the F-40 suspension on the build sheet.

Do you have a build sheet?

Woj

No I don't, haven't really looked.

Did the F-40 suspension include a rear sway bar that went under the rearend pumpkin?

12-bolt was included with the 300hp/350, and was not part of any heavy duty suspension option. The 250hp 350 got a 10-bolt.

All factory 300 hp cars I have seen have had 12-bolts. In fact, I am 99.9% sure that factory 4bbl 350 71-72 cars (270 hp?) had 12-bolts too.

did 69 ss chevelles come with a 12bolt none posi? why would someone order it that way???

Chevy was a bit inconsistent with the 12-bolt thing, but for 1969 ALL 350's, even the regular fuel 4-barrel LM1 (255 horse) used the 12-bolt. In 1970 the 350 2-barrel (250 horse) used a 10-bolt and did on subsequent years. The 4-barrel 350s through 1972 used 12-bolts.

Thanks guys!

According to my Canadian spec sheet the 1969 350s came with 12-bolt rear ends, except that you can't determine whether or not a 2.73 or 2.56 ratio is 10 or 12-bolt. My U.S. drivetrain list for 1969 Chevelles shows that the 10-bolt was used behind 350s with automatics (Powerglide & TH350) because not only does it show the 2.56 ratio with the Hydro & 2.73 with the 'glide, but it also shows 3.08 & 3.36 ratios, which were 10-bolt ratios. So it looks like in '69 the automatics used 10-bolt rear ends.
Sorry for the confusion.

Originally posted by steveracer33:
did 69 ss chevelles come with a 12bolt none posi? why would someone order it that way??? 3.73's on up had a posi
3.55's and down were open and if you wanted a posi you had to order it with one