Stock frames were already long gone by the time Earnhardt posed for that photo. There were chassis builders back then who most of the Cup teams relied on for bare frames or rollers. Laughlin was one of them I believe. Hutchison-Pagan was another. I think Petty Enterprises were building their own cars. The Super teams of that era were already building engines that were light years ahead of the back half of the field but I believe you could get the guy who built your modified or late model engine to put a Cup engine together for you if you wanted to race when NASCAR was at Pocono or Dover (or Trenton) if you had bought a used Cup car from a team who had unloaded last years rolling stock. Its been a long time but I remember reading that as recently as the early 80s one of the top Ford teams was scavenging junk yards for blocks because Ford was so disinterested in spending money in NASCAR. So yeah the engines back then were much closer to stock but still very much a racing engine.