Hi Greg477:

On our 477SD motor the firing order is located as tipperman says "...( cast into the manifold on the left side of the carburetor under the throttle linkage )..." that is the drivers side intake manifold. Also the Firing Order also matches tipperman's as 1-5-4-8-6-3-7-2 with the order on the distributor counter clockwise.

The distributor is mounted with # 1 socket facing the one o’clock position when looking at the motor from the transmission end. When I tried the distributor at the noon position then the vacuum advance hit the passenger side intake manifold.

When I took the distributor out of our truck I used the seasoned mechanics method for reinstalling the distributor. Remove the #1 spark plug (passenger side front), nudge the starter while feeling for compression on the #1 cylinder. (My method was to block the spark plug opening with my finger.) When cylinder reaches TDC the mark on the flywheel should line up with the timing mark. (Note: The mark on the flywheel will also line up with the timing mark when #6 cylinder is at TDC and you do not want that setting.) Now set the rotor to the #1 tower of the distributor and insert distributor into block. Adjust rotor (not distributor) to mesh with cam gear and then adjust distributor to get the correct timing. Remember to make sure vacuum allows for adjustments to distributor before securing distributor. You can move rotor over one tooth as long as you line up the #1 tower with the #1 wire.

PaMnd