Not sore what you are asking ,but there is a 3/8" bolt with a 9/16 head under the distributor. Need more help contact me through my board and I will try to help.
if the shaft is loose in the distributor, you either need to rebuild or replace distributor.if distributor itself is loose there is a bolt at the base of the distributor that holds it in place
To retime the distributor on a 1999 GMC Sonoma, first ensure the engine is at top dead center (TDC) on the compression stroke for cylinder number one. Remove the distributor cap and note the position of the rotor; it should point to the number one cylinder terminal. Loosen the distributor hold-down bolt, rotate the distributor slightly to adjust the timing, and then recheck the timing with a timing light. Once the desired timing is achieved, tighten the hold-down bolt and reassemble the distributor cap.
Through the carburetor or advance or retard the distributor by turning the distributor cap barely left or right. If you cant turn it then loosen the bolt holding the distributor on to the intake with a wrench then turn the distributor til the engine sounds like its not missing or not to where it's about to turn off.
2007 GMC YUKON BOLT PATTERN IS 6X5.5 OR 6X139.7
To adjust the timing on a 1984 GMC 3500 Vandura, first ensure the engine is at operating temperature and set the idle speed. Use a timing light and connect it to the number one cylinder's spark plug wire. Locate the timing marks on the harmonic balancer and the timing tab, and loosen the distributor hold-down bolt. Rotate the distributor slightly until the timing mark aligns with the specified degree on the timing tab, then tighten the distributor bolt and recheck the timing.
what is the plug wire placement on the distributor cap of a1996 gmc 4.3 v6?
the pick up is inside the distributor
turn the distributor.
Bolt pattern for a 1985 GMC Sierra Classic 1500 is 6x5.5 (That is what mine is)
what is the bolt pattern for a 2011 acadia
Cracked distributor cap or bad plug wires
A 2015 GMC 2500 has a 8 on 180mm rim bolt pattern. The dually 3500 has a different 8 on 210 bolt pattern.