another newbie

[clc]

Hi members,
I and a friend have owned two Oliver crawlers for about 15 year or so. the first is and oc-4 that had a bad transmission, but also had bad engine after purchase. we then found an oc-3 in the woods in Oregon, which we purchased for $200. also had a bad engine. we ended up using the oc4's engine which was freshly rebuild and put it in the oc3. and have been using it for years on small jobs. now it is parked with bad starter and runability problems. I live in northern California by the Oregon border. we are looking to put the oc4 together but need to find an engine and transmission parts for it. and fix the starter on the 0c3 and attempt to find out why the engine will only work for about 20 Min's. before it starts cutting out. been a problem for years.