Can anyone verify the thread pitch for these bolts? 3 of 4 are broke off and the forth is probably going to break because it is part way in and that is usually an indication that the PO didn't want to snap it off.

 

I can’t give you the exact sizes and pitches because during the 1990’s GM began transitioning to the metric system for the US model; so the bolts used just depends on where GM happened to be during the transition at the time of production.

So here’s the choices, depending on if it’s the four or two wheel drive shocks you’re installing. You will need to verify the exact size - should be possible even if all you have is a stub.

Google images of hex bolt markings to identify SAE vs METRIC using the markings on the head.

2WD -

SAE 5/16x18 OR 3/8x16

METRIC M8x1.25 OR M10x1.5

4WD -

SAE 1/2x13

METRIC M12x1.75

FYI:

SAE Grade 8 or METRIC grade 10.9 bolts are available at any hardware store and the sizes listed are common sizes. They’re just as rigid as OEM bolts and much cheaper than trying to get these bolts from a parts store.