Hello pietboer.
Welcome to the forum.
Lister D's are one of those engines that have been around since the beginning and constantly changed until the end of production where about 750,000 (hopefully I remembered rightly) were made.
There were a few crankcases and numerous head designs so the height differences may be be obtained.
There were also a few fuel tanks used over the years, and pending on what spec. motor, your tank could be different to the next or last spec. engine. Some were mounted high, some low; some had two compartments, most had one; some where taller then others etc etc.
Your spec. 19D2HK engine sounds like an interesting engine. It is a bit different to the garden variety of Lister D. It is a kero/paraffin engine and has a few items that are very different to the standard petrol burning Lister D's. Have you got any pictures of it?
The spec. number is a bit confusing on your engine. The dating method used from 1950 could also be mistakenly used on your engine making it the 19th engine built in 1952. But it is not. 137736 was built in 1937.
If you want to understand the differences in the Lister D a bit more, a book called "The Lister D Story" by David Edgington is well worth purchasing and reading.
Cheers Scott