My 80 300SD w/OM617.950 has injectors as pictured on left. It may be that style were used in other earlier diesels. But , as you suggest, the rubber ring suggests that they were rebuilt, so they may have been rebuilt for a turbo (higher pop pressure)

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)