I would bring a set of extra Fuel Filters as some Members have pumped bad Fuel into their tanks when buying from Stations they do not normally frequent; it seems to happen more often on trips.
I have 2 pieces of 3/4 inch Plywood screwd together in about and 8 inch square to put under the Jack in case I pull of the Road to change a Tire and I have try to use the Jack in dirt.
I also carry a 12 volt Tire Inflation Pump and a Tubless Tire Plug Kit for on the road tire patching.
I also keep some of the Injector Fuel Return Hose in the Trunk and a spare Strip Fuse for the Glow Plug Relay.

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84 300D, 82 Volvo 244Gl Diesel