block I D - 59-L

[34hardhead]

i would like to know if someone can tell what these letters on the bellhousing area (back top) of the block mean.
The block in question has a 59, then below that is an L.
What does the L mean?

 

[bbrocksr]

Industrial engine, most of the 59L blocks were factory relieved.
Bill

 

[Mike in AZ]

some info that might be helpful.....Mike

http://www.vanpeltsales.com/FH_web/flathead_specs-85to100mid.htm