Stan contacted me by email regarding the Lister thermostats that were listed in the early parts books, and I thought the information might be of use to others so have posted it to the forum.
Two thermostats are listed, both for Tank-Cooled engines ONLY:
Thermostat complete assembly 8-2-181 for 1-1/4" Radiator Hose
Thermostat complete assembly 9-2-181 for 1-5/8" Radiator Hose
Thermostat element only 8-2-185
I cannot find any illustrations of the parts in the books, and this seems only to be listed in the later 1967 Book 103, there is no mentioned in the 1951 issue.
Thus there is no separate housing to bolt on, these were fitted in the hose line to the tank.
A water pump is also listed for tropical spec engines.
Hope this is of some assistance.
Peter