115-490-05-19 is for 240D W115 chassis up to 200000.
115-490-13-19 is for 240D W115 chassis 200001 onward.

1976 was the last year of production for the W115 240D. so you probably need the second version.

Hope this helps.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022