Just came home with my new 1st Gen. I love how easy this truck is to work on, compared to a 2nd gen. I originally thought the vacuum pump had a small leak, no big deal, I've rebuilt them before and always had good support with Gould gear out of NC, great guys to deal with IMHO.
Either way, once I took a closer look, I noticed the oil leak was actually because the timing pin was missing, and someone had shoved a small rag in the hole. A new pin and o-ring from Pure Diesel products and we were back in business. A little trick, if you have trouble getting the retainer clip into the groove, I found a little high-temp grease allowed to it stick to the end of a deep socket and a gentle tap got the job done.