1980 Stepside Build... My first build thread

[ChevDog1]

I have spent way too many hours over the last 10+ years on forums for various cars, reading build threads, giving and receiving repair advice, and generally living vicariously through others. Between about 2003 and 2010, I built up a rally nice 1995 Jeep YJ, using information found online, and learning as I went.

Last fall, wanting another project for my hobby, and to relive a bit of my youth, I purchased a 1980 stepside for my next project. I feel that it's time I "give back" a bit to the online communities that I have received so much knowledge from over the years, and share some of my experience with this latest project.

my starting point is a very basic 2wd C10 stepper. Still has the original 250 straight six (going to keep it). It was originally equipped with a 3 on the tree, but a misguided former owner replaced it with a "turbo 350 (more on that in a minute). I bought the truck locally for $950 in non-running condition and had to rent a uhaul trailer to get it home. The PO had stripped all of the emission equipment from it, and kept the HEI distributor for another project of his.

The first order of business was to get it running. The PO told me that it ran ok, but when he finished the trans swap, he said that it vibrated badly, like it had a dead cylinder, and the trans wouldn't shift out of first gear. I sourced a rebuilt dist. From Napa, and go to it running - and he was right- it shook pretty badly at anything over an idle. My first test drive showed that it would not shift from first gear, just as he said. Further inspection showed that the trans was not a 350, but was in fact a TH400, and he had not hooked up the vacuum modulator. a simple length of brake line, and a couple of chunks of vacuum hose had the tranny shifting as it should.

Now - the vibration. Knowing that most TH400's came behind 454's, which are externally balanced, I crawled back under the truck to confirm my suspicion. He had used the flexplate from the 454- which was causing the vibration! A few minutes with a cold chisel to remove the balance weight, and the little six was as smooth as glass.

Here is what I started with...