Hi! My name is Jim and I bought a 1982 GMC 1500 Sierra from my father-in-law. It has the 6.2L diesel with 112,000 original miles. The truck runs good but is gutless starting from a stop going up a grade. It shifts out of first at 15 mph, and out of second at about 20 mph going up the hill I live on. (15% grade) I have to manually shift back down to 1st gear or it will only do 20mph going up the will, which has a 30 mph speed limit. On the highway it takes hills at the speed limit. Are these just gutless or do I need to look at something?
Thanks,
Jim