Axle codes.....

[87Limited2Turbo]

Quote from gnttype.org "The rear axle ratio, differential type, manufacturer, and build dateinformation is stamped on the right axle tube (as viewed from the front of the car) on the forward side"

with that said, i was getting numbers of my rear end today and i have these...
6TP G 028 EXCEPT mine are on the left side....gnttype did list a 3.42 from an 84 turbo with GTP 99% sure its a 6 though, but whats with the G ?
next quote "The first 3 digits indicate the axle code, the next one indicates manufacturer (B=Buick, O=Olds, C=Chevy, P=Pontiac), the next is Julian date it was built and the last it the shift it was made on"

so what exactly is this rear end ? it is positive track (black marks prove that lol)
the car was an 83,84 cutlass not sure which, that was put on a GN frame. motor is 86-87 GN, trans is 200R4, just curious what rear end i have.....

 

[mikestertwo]

Post a pic of it from the back (pic of the cover). We can tell you if it is a 7.5" or 8.5". If it's a posi just jack the rear off the ground, put the trans in neutral, then turn one of the rear wheels exactly one revolution while counting how many times the pinion turns. That will tell you what gears you have.

 

[87Limited2Turbo]

pretty sure its an 8.5

 

[novaderrik]

forget the codes. pop the cover and take a look at what you have.
regardless of what it was originally installed in, an 8.5 for a g body is a somewhat rare beast.
unless it's had a gear swap done, it will either have 3.42 (84-87 TR) or 3.73 (84-87 Hurst Olds/442) gears.
if it's a posi like the tag indicates, then so much the better.

 

[mikestertwo]

pretty sure its an 8.5

Definitely an 8.5" rear. Turn the wheel one turn and count the pinion rotations that will give you the gearing.

 

[87Limited2Turbo]

yes its definatly positive track cause i had 2 black marks everywhere i smoked the tires lol (smokey burnouts i like to call em) me and a friend did the one wheel rotation while moving the car in drive slowly. he spray painted a mark on the driveshaft and i eased it across paking lot very slowly as he counted the drive shaft rotations and he said best he could tell it looked like about 3 and a half turns....so im figuring 3.42's i was just curious about the numbers as to whether or not the rear actually came out of a GN or something else (442, Monte SS, etc...) i will pull the cover and be sure. where exactly are the numbers inside ?
i only gave 800 (650 and a wrecked Rustang i wanted 150 for) for the cutlass and so far the i have a running GN motor(86 or 87 intercooled), very good 200r4, positive rear end, front frame braces, the gn fuel tank, and a few other small things. i figure i got my money's worth lol. the day i went to look at it the guy pointed to the intercooler and said, and i quote "look, its even got a cold air kit installed on it" i couldnt help but laugh. he knew it was a gn motor but i really think he had no idea what it was worth. he said no one who looked at it would give him 800.00 . 500 was the best offer he got. i never hesitated at 800 cause i knew it was a steal.
i just couldnt understand why the numbers were on the opposite side of the rear end and didnt match the axle codes for the 86-87 GN's.

thanks for the help guys...

 

[mikestertwo]

just curious about the numbers as to whether or not the rear actually came out of a GN or something else (442, Monte SS, etc...) i will pull the cover and be sure. where exactly are the numbers inside ?
thanks for the help guys...

The rear came out of a GN. 442's and Hurst Olds had 3.73's. SS Monte's had 7.5" rears. If you feel the need to pull the cover to verfiy ratio, the tooth count is stamped on the ring gear or you could just count the teeth and do the math.