frame and 3.55 posi value
 

I hate to ask these questions, ive been out of the GTO game for so long, im not familiar with currant values. If I end up selling or parting out a car looking for an honest value for each part separately.

Year of both?

Sent from my moto z3 using Tapatalk

both 69

Hardtop frames don't seem to pull much money unless they are rustfree but currently in the rustbelt where there will be demand for them. Convertible frames pull good money but they obviously have to straight and rustfree.

3.55 STT diff's (meaning the whole rear end assembly with axles etc) seem to be worth $500-$1,000. Obviously mechanical condition of the diff itself matters but the date on the housing matters with later dates being more in demand than earlier ones (probably because of demand by Judge owners).

I bought a 3:55 posi with the 'N' cast on the housing for $600 a few years ago. Originally from a '69 GTO.
As I recall, that's a 4 pinion nodular rear. Seems to be about the average price range from what I've seen.

Iirc it's the series three STT that triggers the nodular rear and 4 pinion unit, 3.36 and up numerically.

The exception is GP's, they used a 4 pinion STT on the 3.23 axles which would have a 2 pinion on an A or F body. Not sure why, perhaps the extra weight of the G body and/or the optional 428 engines?

68 69 70 the 3.55 STT could be Regular or Nodular (N) HD

HD (N) was extra cost on those STT vs STT-HD
3.90 & 4.33 were the only ones that were default HD with STT

Bill you need to check the housing for a big raised N on topside of housing.
More value with it

In 69 (and in 68 and 70 except for the 455 i believe) )you never could choose between the HD and regular version of STT, it was determined by axle ratio...

All GTO's with 3.36 or higher (numerically) axles that were ordered with an optional limited slip were the 4 pinion HD-STT at $63.19. 3.23 or numerically lower with limited slip were the standard 2 pinion STT at $42.13.

In theory all the 4 pinion STT's (HD) should also have had the N (nodular) housing but perhaps that didn't always happen.

With 3.90 and numerically higher axles HD-STT was mandatory.

Just a note , The standard SST differential would have a part # 9795082 casting which is the 2 pinion carrier.
The HD SST which is 3.55, 3.90, 4.33 has casting 9795084 which is the 4 pinion casting with the N on the top.
Very hard to find and worth at least 1000 from what I have seen.

That much just for the carrier, or complete rear ? Thanks everyone for the info

The whole thing drum-to-drum
But you have to check for the N on top and the casting number to get in that range.

Would also need to be a clean part with minimal pitting and an internal inspection.
Rusty pitted dirty with unknown condition internally won't bring those figures.

I have a 68 3.55 posi and a 70 3.55 posi - neither with N casting
it makes a difference

I'd gladly pay more than that if I could find a Nodular 3.55 for my late-68 build 69 Firebird Sprint.

I guess I got a pretty fair deal on this one then. Still haven't gotten around to installing it.https://uploads.tapatalk-cdn.com/202...b94a5d564f.jpghttps://uploads.tapatalk-cdn.com/202...85989ad77d.jpg

Sent from my moto g(6) play using Tapatalk

I think I have been fortunate to accumulate a batch of 3.55:1 Nodular STT rear ends for my 68 GTOs. I don't believe I currently have any spares, and nothing currently for a Firebird. I sold 3 Firebird positraction differentials about 6 years ago.

I know of a guy in town here who might have one though...I'll check with him.

Off topic but....Kurt, do you or your friend have a drivers side tinted quarter glass for my '68? I'll hang up and listen for your answer offline. :)

Looks like i got lucky, N casting on the housing. Now just need to decide which car to build , probably the mayfair maize vinyl top, manual trans car,and get rid of some of the other projects.

I sold a 68 a-body N 3:55 last summer for 800 couldn't read the axle tube code. I had the rear cover off for inspection and the first guy that showed up took it. fwiw

I forget if my former 69 Sprint 4-speed had the N on top the Case ( 3.55;1 Posi ). I remember seeing an N but forgot which car..

Ive had some ask if the rear is for sale , would rather sell the car with frame with shell together.

Looks like i got lucky again, another one of my cars i knew was posi, even though its a 71 2.78 open housing.
It ended up having a 3.36 posi that someone swapped in, so thats the lower end carrier for 3.55, 3.90 etc... At one point pinion had gotten loose and made some marks on the outside of the case , but dont think its an issue to run.