assign multiple resources by function with different working times

Forgive me I am new to this forum and I don't know whether this question has been answered previously.

Basically as an example, if I have a mechanical task that requires an amount of technicians work say 400 manhours, however the technicians that will be working on it have different shift patterns. How do I assign the resources by the technician 'group'. The aim being to effectively level the resources over a shift system.

Many thanks for your help.