Just a suggestion...when you pull the harmonic balancer to get at the seal, pay special attention to the area on the neck where the seal rides. If it is heavily grooved you can pick up a FelPro "quick sleeve" that slides over the neck of the harmonic balancer and gives you a true surface for your seal. These are available from most any of the major parts houses or by mail order.
Secondly, when changing out the timing case seal, it is suggested that you loosen the timing cover, apply a little grease to the newly installed seal, press or draw on the balancer, centering the seal and after the balancer is fully seated, tighten the timing cover bolts. This will guarantee a good seal.
The down side of this procedure is that you'll have to drop the pan to get the 2 bottom cover bolts loose from the front main cap. Now would be a good time to remove the main cap, tap them to 3/8" drill out the 2 bottom holes to 3/8+ so you can install your cover bolts all from the outside. This is a one-time fix and will save you time and headaches down the road.
Dave
BTW...nice looking truck!!
