I have the following stamping on the rear end (bottom of tube - driver's side) on my 70 GS: ON W (or maybe N) 258 (there is a bout a 1" space between the "ON" and the "W") Can any one help on decoding that? The stamping is real poor as it is right on the crease of the tube and only about 1/2 of all those letters/numbers are even stamped in. But I'm pretty sure this is how it reads. Thansk for the help! Ross
ON is the gear code.....3.64 W is for Warren Manufacturing plant 258 is for the day of the year. There should be another number after such as 1 2 or 3
8.2 inch ring gear 3.64 ratio = ON w= posi traction but if the w is immediately to the right of the ON with no letters in between it is the code for the manufacturer of the rear axle. In this sequence the W = Made by Chevrolet at the Warren Plant. So W = Warren plant. 258 means it was built September 15, 1969
Thanks guys for the info. The car is a Stage 1 1970 GS, built in Flint (invoice date = Sept 23, 1969). Does it makes sense this would be original rear end (Did the Chevy, Warren plant supply Buick? I read somewhere that the Posi's in 1970 had the O with an X inside - to indicate posi and 3.64. Or am I confused on that. ^Thanks again, Ross
Yes Chevy and Pontiac did supply Buick with some items like frames and rear axle assemblys. The dates make sense to me. What is the problem that you see?
