When replacing your 103 engine timing chain it is also important to replace the chain tensioner.
190E 2.6 300E 300SE Timing Chain Tensioner - 103 Engine
$72.00
SKU:
GRG-COM103CT 
Product Details
Applicable Benz are the 6 cylinder 190E or 124 chassis 300E (CE and TE) or the 126 chassis 300SE / L with the single cam gas engine. To order timing chain look below.
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$59.00
190E 2.6 300E 300SE Timing Chain and Link - 103 Engine
Don't lose your high mileage (above 150,000 miles) 103 engine due to a failed timing chain. If this chain breaks at high speed it can destroy the engine.