If you want to check the timing for cheap, you need:
a 7MM solid core wire and ends...try a small engine repair shop, lawn mowers and such...
Autolite #275 plug, the civvy equivalent
Put the ends on the wire and remove the stock wire and plug from #1 cylinder. Carefully push the timing wire you made through the lid and into the cap until you are sure it is fully seated.iiit is possible to break the tower on th cap where the wire goes down through it so be careful or you'll be buying another cap...just go easy...then put in the new plug and hook the wire to it. You can pull another vehicle, 12 volt, up near the truck or use a 12 battery that has charge, to power the timing light. Clip the lead on the new wire and time away.
It is very common to buy an M715 and find the timing 40 or more degrees off....
brute4c