The Rivers had 2000 gallon tanks - and 'J' class very similar - while the 'L' class had 2,700 gallon initially and a little less when modified ....... even the 3500 gallon tenders of the 'U' class rebuilds gave a comfortable increase. ( Perhaps a little surprising that the - very non-standard - 'J' class survived so long ...... and their SECR namesakes, for that matter.)