I have a '78 K5 that is a full time 4wd version. I have heard about the mile marker conversion kit but just curious if anyone has any experience with it. Does it require extensive amounts of labor to install? Does it actually improve on road performance such as on the highway? Mine has a top speed of about 50 mph and tends to grab a little when making turns. I have found them for $100 online but didn't want to drop the coin if it won't give me any performance enhancements.