I am trying to build a case/if statement in a JOIN ON clause.
JOIN ON
LEFT JOIN [CTSTRC] [Statuses] ON RIGHT([Statuses].[STRID], 3) = [CTE].[F61]
You might want to try something like this
select ... from CTE inner join ( select ... from [Statuses] where ISNUMERIC(STRID + '.0e0') = 1 ) rsNumeric on CTE.F61 = rsNumeric.STRID