I know I've seen hand throttles discussed here before, but I wasn't aware that GM factory installed them. Looking through my parts manual, a "1988-89 'RV' Cable Asm, Hand throttle" is shown. Some of the part numbers look like ones that have been around awhile, only application I can think of is for PTO? Some of the part numbers are: 340696 340697 326585 Was going to check availability on gmpartsdirect.com just for the heck of it, but they are down for maintenance. Interesting setup.