Can anyone help me identify my Lister D ??

[brainshbsuk]

Hi Forum,
I have just purchased my first lister engine & am in the process on rebuilding. I have done some research on the internet & purchased a couple of books but cannot identify the exact model. The plate says SPEC 26DHR, 700RPM, 1 - 1/2HP NUMBER 171746. The exhaust is on the left & the carb is on the right ( which seems unusual ) I beleive the engine runs anticlockwise Can anyone advise.
Regards
Brian..

Moderators.   If I have posted this in the wrong forum coluld you please move into correct forum as this is my first post..