I used a vacuum switch for 85 1/2 ton Silverado also, used a diagram from
www.montecarloss.com to wire it, had to remove pan & cut a couple wires & reconnect another one or two. Cost next to nothing. The driveshaft I used supposedly came from shortbed Silverado of similar vintage, I didn't even cut it, fit fine(still not sure how that happened). I used a Q-jet baseplate & throttle bracket TV cable all for 85 1/2 ton Silverado so adjustment was easy, shifts good. Brian
