I just had that tank replaced by Red Devil up here with a later model one. Those ones are apparently prone to cracking, as yours show.
***Edit***
Assuming it is the plastic tank that has cracked
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The tank cost $150. The labour for replacing that and lancing the radiator was $45. New Coolant that is apparently really good cost $50 for the 5 litres, but they do have a cheaper one.
Pete
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OFR #23
Member - ATPS - Automatic Transmission Preservation Society