Originally Posted by Sadler

In 77-79(RV style) and '80 until '84 they came with a 496cc type 503 fan cooled twin in the 5500/5500MX, and a 336cc type 354 L/C for the 340 in the 6500/7500Plus and a 436cc type 454 L/C for the 440 in the 9500Plus flavor and '83/84 saw the 9700Plus with the 521cc 534 type motors, dispute that with any Doo-minded person, I know my Doo-Facts on these models, it's just that the 7500's were overshadowed by the bigger 9500's and there aren't as many of them around then or now.