speed sensor

I have a coachmen MH. and i want to install a navigation system... Does the GM 454 MH chasses have a speed sensor.. If not , can there be one installed? If there is one can you tell me where its located..I understand that a speed sensor must be hooked up for the nav. system to work right... Thanks for any help...
speed sensor

Forgot to list year... It is a 1986 but only has 53,000 miles. I dont know when the first year was for an electronic speed sensor..