MPFD

iTrader: (5)

Is there an RPO code or an other indicator that will let me know if I have 28 or 30 spline axles? I have a 99 silverado that cam with a 5.3, G80, and 3.73...
Any one know?

99LsSilverado

iTrader: (3)

You should be able to call your local dealer and give them your vin and get that info for you.

dlt76028

iTrader: (13)

30 spline....

MPFD

iTrader: (5)

Thanks I didn't know if it might be a 28 spline being the first year. 99 models seem to be an odd year where parts are concerned.

1Bear

iTrader: (1)

No guarantees, but my friends ’99 SBSC had 30 spline axles in his.

fastrt

iTrader: (48)

30 spline 8.6 rear. only s-10 and f-body 7.5's had 28 spline I think. but I am sure yours is 30!

Jordan927

iTrader: (1)

+1

All 8.6" have 30 spline.

Some of the 8.5" axles had 28 Spline.

MPFD

iTrader: (5)

I called Jaws to order a trutrac and they told me it could be either and i had to tear it apart to tell. Not really into that!

Jordan927

iTrader: (1)

That's because the TruTrac is made to fit 8.5" rear ends...the 8.6" happens to be the exact same rear end except its .1" larger.

I have never seen a 28 spline 8.6" rear. And if I am not mistaking the G80 is not made in 28 Spline.

913A481 is the P/N you want.

That's for 88-09 trucks with 30 spline 8.5" and 8.6" diffs
The last 8.5" made with 28 spline was 1989.

dlt76028

iTrader: (13)

its an 8.5/8.6 30 spline without doubt.