I converted my '83 Puch Odyssey to downtube shifters. I bought some NOS Suntour Cyclone shifters (still in the box!) off Ebay and installed them along with a NOS Suntour Cyclone MKII RD (also from Ebay). My bike has a little stop welded on the frame where the cable stop was on the downtube to keep it from slipping. I used that to keep the new shifters from slipping and it worked great. Shifts much better now as well, plus it looks cleaner. Switch it over and ride it!